Grüneisen γ通用函数及完全物态方程

在分析Grüneisen γ近似函数的适用范围和热力学γ高压演化特性的基础上, 根据Grüneisen γ系数的物理性质和变化特点, 利用数学分析的方法建立了Grüneisen γ通用函数γ_n(v). 将γ_n(v)代入热力学函数γ(v, T), γ(v, T)即成为全压力区连续可导的函数, 并由γ(v, T)直接导出了等熵温度函数T_S(v); 再根据等熵温度与Hügoniot 温度的函数关系获得了Hügoniot温度方程的解析函数T_H(v), 从而使Hügoniot方程成为完全物态方程. 对几种金属做了检验, 由等温方程推算Hügoniot方程, 或者由Hügoniot方程推算等温方程, 其结果都与实验符合得很好.     

轮烯衍生物电子结构及三阶非线性光学性质的理论研究

苯轮烯衍生物具有良好的非线性光学性质. 运用密度泛函理论在不同理论水平和不同基组下计算了轮烯衍生物的静态极化率α和静态第二超极化率γ. 采用含时密度泛函TD-B3LYP方法计算了轮烯分子的紫外吸收光谱. 结果发现: 弥散函数对静态线性极化率α和第二超极化率γ 的计算结果都有显著的影响; 共轭体系的大小和引入的推拉电子基团可以调节轮烯衍生物的第二超极化率. 添加推拉电子基团后不仅能得到更高的非线性光学系数, 也能保证有较好的透光性能, 表明轮稀分子兼具有较高的三阶非线性光学响应和在可见光波段具有良好的透光性的特性. 此外, 采用CAM-B3LYP方法计算了分子1-1和分子2-2的动态(超)极化率. 计算结果表明: 在近红外区, 随着入射光频率的增大, α (ω; ω), γ (-ω; ω, 0, 0) 和γ (-2ω; ω, ω, 0) 都随之增大, 出现近共振增强效应; 在远离共振条件下, α (ω; ω), γ (-ω; ω, 0, 0) 和γ (-2ω; ω, ω, 0) 变化平缓.     

增长速度对合作网络参与者节点度分布的影响

采用率方程对合作网络自组织演化模型进行解析,得到参与者节点度分布服从Yule-Simon分布,这种分布可以用漂移幂律分布近似.分析参与者节点增长速度与参与者节点度分布之间的关系,发现随节点增长速度加快,参与者节点度分布远离幂律,表明节点增长速度是除优先连接之外的另一个影响合作网络拓扑性质的重要因素.通过对城市公交网络和科研合作网络的实证研究,验证了度分布解析结果的正确性.结合实证研究,探讨了合作网络中参与者节点增长速度的形成机制及其实际意义.     

20—50MeV O5+离子引起Au的L壳层X射线产生截面研究

在北京13 MV串列加速器上利用20—50MeV O⁵⁺离子研究Au的L壳层X射线产生截面. 实验结果表明σ（Ll）/σ（Lα） ,σ（Lβ）/σ（Lα） 和σ（Lγ）/σ（Lα）与EＣＰSSR理论计算结果符合比较好.在实验中由于较高的能量,在能量点存在能移现象. 关键词： 产生截面 ECPSSR X射线     

非线性漂移的Fokker-Planck方程的近似非定态解

研究了由高斯白噪声和色噪声作用下的非线性动力学系统的不稳定态演化问题. 在弱噪声极限下, 运用本征值本征矢理论得到了非定态解ρ(x, t)的近似表达式; 分析了色噪声自关联时间τ, 强度α对ρ(x, t)以及对一、二阶矩的影响. 数值模拟发现: 1)t在一定范围内, ρ(x, t)是变量x和t的单调函数, 且随τ的增大而增大, 反之, 随α的增大而减小; 2)一阶矩是τ和α的单调函数, 但二阶矩却是非单调函数, 在参数影响下发生了相变现象. 关键词： 奥恩斯坦-乌伦贝克过程 本征值 本征矢 非定态解     

PS自由基X2Π态的势能曲线和光谱性质

采用Davidson修正的内收缩多参考组态相互作用方法(icMRCI+Q) 结合Dunning等的相关一致基计算了PS自由基X²Π 态势能曲线. 利用三阶Douglas-Kroll Hamilton近似结合cc-pV5Z相对论收缩基进行了相对论修正计算. 利用aug-cc-pCV5Z基组对势能曲线进行了核价相关修正计算, 并将总能量外推至完全基组极限. 拟合得到了X²Π态的主要光谱常数R_e, ω_e, ω_ex_e, ω_ey_e, B_e, α_e 和D_e, 与实验结果符合较好. 利用Breit-Pauli算符, 研究了旋轨耦合效应对势能曲线的影响, 得到了两条Ω 态的势能曲线. 详细分析了在旋轨耦合计算中, 核电子相关与冻结核近似对电子结构和光谱性质的影响. 在icMRCI+Q/56+DK+CV+SO理论水平上得到了两个Ω 态的主要光谱常数T_e, R_e, ω_e, ω_ex_e, ω_ey_e, B_e 和α_e, 结果与实验结果一致. 在平衡位置处, 本文的X²Π态旋轨耦合能量分裂值为 323.73 cm^-1, 与实验结果321.93 cm^-1较为一致. 通过求解双原子分子核运动的径向Schrödinger方程, 找到了无转动PS自由基X²Π态及其两个Ω 态的全部振动态, 还分别计算了它们相应的振动能级和惯性转动常数等分子常数, 这些结果与已有的实验值一致. 关键词： 势能曲线 光谱常数 分子常数 旋轨耦合     

氧离子轰击引起钽的L壳层X射线发射截面的研究

在北京原子能研究院串联加速器上,利用20—45 MeV的O⁵⁺轰击Ta靶,研究靶的L壳层X射线. 给出了Ta的L壳层各亚壳层Ll,Lα,Lβ和Lγ X射线发射截面的比值,并且与ECPSSR理论计算做了比较. 结果表明,在误差范围内比值σ(Ll)/σ(Lα)、σ(Lβ)/σ(Lα)和σ< 关键词： L壳层X射线')" href="#">L壳层X射线 发射截面 ECPSSR理论     

色关联噪声对林木Logistic生长模型的影响

在林木生长Logistic模型中, 引入加性和乘性关联色噪声, 运用统一色噪声近似、刘维方程以及诺维科夫原理, 推导了近似福克-普朗克方程, 分析了相关参数对稳态概率分布函数的影响. 结果表明: 改变乘性色噪声强度D和加性色噪声强度Q均能导致稳态概率分布曲线峰值高度的改变以及峰位置的移动, 对概率密度分布呈现出漂移作用. 但是在D和Q增大的过程中, 稳态概率分布曲线峰位置的移动方向是不同的: D增大时, 峰的位置向左移动; Q增大时, 峰的位置向右移动. 另外, 当λ >0时, 随着|λ|的增大, 稳态概率分布函数峰的位置向右移动, 且峰值的高度变大; 而λ<0时, 随着|λ|的增大, 稳态概率分布函数峰值的高度也变大, 而峰的位置却向左移动. 关键词： 林木生长 Logistic模型 色噪声 稳态概率分布     

肖特基势垒对CdS/CdTe薄膜电池J-V暗性能的影响

采用数学模拟方法分析了不同背接触势垒高度(φ_b) 对于CdS/CdTe薄膜电池的J-V(电流密度-电压)方程的影响, 得出了势垒高度与roll-over的变化对应关系. 采用相应Cu/Mo背电极的CdS/CdTe薄膜电池在220-300 K的变温J-V曲线的数值分析与理论分析相对照, 分析了背势垒对于J-V曲线拟合参数的影响. 修正了φ_b 与反向饱和电流(J_b0)关系式, 理论与实验符合得非常好. 关键词： CdS/CdTe薄膜 伏安特性 肖特基势垒 roll-over     

一类高聚类系数的加权无标度网络及其同步能力分析

针对真实世界中大规模网络都具有明显聚类效应的特点, 提出一类具有高聚类系数的加权无标度网络演化模型, 该模型同时考虑了优先连接、三角结构、随机连接和社团结构等四种演化机制. 在模型演化规则中, 以概率p增加单个节点, 以概率1–p增加一个社团. 与以往研究的不同在于新边的建立, 以概率φ在旧节点之间进行三角连接, 以概率1–φ进行随机连接. 仿真分析表明, 所提出的网络度、强度和权值分布都是服从幂律分布的形式, 且具有高聚类系数的特性, 聚类系数的提高与社团结构和随机连接机制有直接的关系. 最后通过数值仿真分析了网络演化机制对同步动态特性的影响, 数值仿真结果表明, 网络的平均聚类系数越小, 网络的同步能力越强. 关键词： 无标度网络 加权网络 聚类系数 同步能力     

A Collaboration Network Model with Multiple Evolving Factors

To describe the empirical data of collaboration networks,several evolving mechanisms have been proposed,which usually introduce different dynamics factors controlling the network growth.These models can reasonably reproduce the empirical degree distributions for a number of well-studied real-world collaboration networks.On the basis of the previous studies,in this work we propose a collaboration network model in which the network growth is simultaneously controlled by three factors,including partial preferential attachment,partial random attachment and network growth speed.By using a rate equation method,we obtain an analytical formula for the act degree distribution.We discuss the dependence of the act degree distribution on these different dynamics factors.By fitting to the empirical data of two typical collaboration networks,we can extract the respective contributions of these dynamics factors to the evolution of each networks.     

Widths of conduction bands in metals

The widths of the conduction bands in metals have been calculated by using experimental plasma-loss values. The calculated bandwidths are in fair agreement with those observed experimentally for K, L and M X-ray emission.     

Effect of bare mass on the Hosotani mechanism

It is pointed out that the existence of bare mass terms for matter fields changes gauge symmetry patterns through the Hosotani mechanism. As a demonstration, we study an SU(2) gauge model with massive adjoint fermions defined on M⁴S¹. It turns out that the vacuum structure changes at certain critical values of mL, where m (L) stands for the bare mass (the circumference of S¹). The gauge symmetry breaking patterns are different from models with massless adjoint fermions. We also consider a supersymmmetric SU(2) gauge model with adjoint hypermultiplets, in which the supersymmetry is broken by bare mass terms for the gaugino and squark fields instead of the Scherk–Schwarz mechanism.     

Determination of shallow core level spectra in selected compound semiconductors

Core level spectra of the M shells of Ga, Ge, As, and Se and of the L shell of S have been obtained from X-ray photoemission measurements on GaAs, GeSe, and GeS. Broadening contributions from the achromatic source, the analyzer momentum window, and the extrinsic losses experienced by the photoemitted electrons in traversing the solid, as well as satellite lines due to K_3,4 emission, are removed by deconvolution of the data with a measured electron backscatter spectrum convoluted with a source function. The results are compared with theory where available.     

Unified neutron star EOSs and neutron star structures in RMF models

In the framework of the Thomas-Fermi approximation, we systematically study the EOSs and microscopic structures of neutron star matter in a vast density range with n_b ≈ 10⁻¹⁰-2 fm⁻³, where various covariant density functionals are adopted, i.e., those with nonlinear self couplings (NL3, PK1, TM1, GM1, MTVTC) and density-dependent couplings (DD-LZ1, DDME-X, PKDD, DD-ME2, DD2, TW99). It is found that the EOSs generally coincide with each other at n_b ≲ 10⁻⁴ fm⁻³ and 0.1 fm⁻³ ≲ n_b ≲ 0.3 fm⁻³, while in other density regions they are sensitive to the effective interactions between nucleons. By adopting functionals with a larger slope of symmetry energy L, the curvature parameter K_sym and neutron drip density generally increases, while the droplet size, proton number of nucleus, core-crust transition density, and onset density of non-spherical nuclei, decrease. All functionals predict neutron stars with maximum masses exceeding the two-solar-mass limit, while those of DD2, DD-LZ1, DD-ME2, and DDME-X predict optimum neutron star radii according to the observational constraints. Nevertheless, the corresponding skewness coefficients J are much larger than expected, while only the functionals MTVTC and TW99 meet the start-of-art constraints on J. More accurate measurements on the radius of PSR J0740 + 6620 and the maximum mass of neutron stars are thus essential to identify the functional that satisfies all constraints from nuclear physics and astrophysical observations. Approximate linear correlations between neutron stars' radii at M = 1.4M_⊙ and 2M_⊙, the slope L and curvature parameter K_sym of symmetry energy are observed as well, which are mainly attributed to the curvature-slope correlations in the functionals adopted here. The results presented here are applicable for investigations of the structures and evolutions of compact stars in a unified manner.     

格子Boltzmann方法分析加热尺寸和瑞利数对可变形开口腔内自然对流的影响

采用格子Boltzmann方法对可变形腔体内自然对流问题进行数值研究，给出平均努赛尔数的经验关系式.腔体左壁加热长度分为左壁面的整个区域（H）和左壁面的中间区域（0.5H）两种情况，右壁向外界环境开放，上下边界绝热且可以上下移动，以此调节右出口尺寸.主要研究瑞利数（10⁴ ≤ Ra ≤ 10⁶），右出口尺寸（1.0H ≤ L ≤ 2.0H），左壁加热尺寸（L_h=0.5H或L_h=H）对腔体内等温线、流线、局部努塞尔数和平均努赛尔数的影响.结果表明：腔体内换热随着瑞利数的增大越来越强烈，表现为椭圆形准静止区域更加靠近上绝热壁，且热分层厚度逐渐变小，平均努赛尔数增加.而右出口尺寸的增加，对于两种加热尺寸下腔内的换热效果有不同程度影响，其中与加热尺寸为左壁面的全部区域L_h=H相比，加热尺寸为左壁面的中间情况L_h=0.5H时，右侧开口尺寸的增加对换热效果的影响不显著.此外，左壁加热尺寸为0.5H时显示出比加热尺寸为H时更高的平均传热效率.最后，针对不同的加热尺寸，提出加热面平均努赛尔数与Ra数及右壁面开口尺寸L^*之间函数关系的经验预测，拟合效果满足工程实践与设计需要.     

Steady state and relaxation spectrum of the Oslo rice-pile model

We show that the one-dimensional Oslo rice-pile model is a special case of the abelian distributed processors model. The exact steady state of the model is determined. We show that the time evolution operator for the system satisfies the equation where n=L(L+1)/2 for a pile with L sites. This implies that has only one eigenvalue 1 corresponding to the steady state, and all other eigenvalues are exactly zero. Also, all connected time-dependent correlation functions in the steady state of the pile are exactly zero for time difference greater than n. Generalization to other abelian critical height models where the critical thresholds are randomly reset after each toppling is briefly discussed.     

Spectra of quantum chains without the Yang-Baxter equation

We study one-dimensional reaction-diffusion models described by master equations and their associated two-state quantum hamiltonians. By choosing appropriate rates, the equations of motion decouple into certain subsets. We solve the first subset which has a close relation to the problem of lattice electrons in an electric field. In this way we obtain L(L − 1) + 1 energy levels of a quantum chain with L sites. The corresponding hamiltonian depends on seven parameters and does not look integrable using conventional methods. As an application, we compute the dynamical critical exponent of a new type of kinetic Ising model.