硼原(离)子内壳激发高自旋态能级和辐射跃迁

采用Rayleigh-Ritz变分方法计算了B原子(离子)内壳层激发高自旋态(~(4,5,6)L,L=S,P)里德伯系列的能量和精细结构劈裂,利用截断变分方法改进非相对论能量,并利用一阶微扰理论计算了相对论能量修正和质量极化效应修正,利用屏蔽的类氢公式计算了量子电动力学效应和高阶相对论效应,从而得到了高精度的组态能量.利用精确计算的波函数,计算了这些高自旋态的电偶极辐射跃迁波长、振子强度和辐射跃迁概率.通过长度规范和速度规范计算的振子强度的一致性证明了本文计算的波函数是精确的.相比其他理论计算结果,本文计算的高自旋态的能级及跃迁波长数据与实验数据符合得更好.对于一些高位的内壳层激发高自旋态,相关的能级和跃迁数据为首次报道,本文的计算结果对相关实验光谱谱线标定具有重要意义.     

辐射复合截面的扭曲波计算

采用非相对论量子计算方法计算了电子与高电荷态离子碰撞的辐射复合截面, 其中连续态电子的波函数是由扭曲波近似方法(DWBE)获得. 计算了低能电子与中、低核电荷的高电荷态离子(类H和类Li)的辐射复合截面, 并与采用有效电荷的库仑波计算结果进行了比较, 说明了扭曲波计算的重要性.     

高剥离态Au、U离子电离势的相对论计算

采用全相对论量子力学GRASP 2程序平均能级AL模型,考虑到核的有限体积效应、Breit和QED效应,系统地计算了金和铀的高剥离态的部分离子态的电离势,将所得的计算结果和文献报道的实验值进行比较.结果表明,考虑高剥离态原子的高阶修正后,高剥离态离子的电离势的计算值与实验数据之间的误差基本消除.     

类铍离子激发态的能量计算

采用多组态相互作用方法及Rayleigh- Ritz变分法,计算了类铍O4+离子1s22s2p3Po态的非相对论能量,并详细分析了如何选择质量最好的变分波函数.运用截断变分方法进一步饱和函数空间得到能量的改进量,并考虑相对论修正、质量极化效应等获得了相对论能量计算值.计算结果表明,此理论计算方法可得到高精度的能量计算值.     

电子与Mg5+碰撞激发的碰撞强度研究

采用多通道R-matrix程序计算了电子与Mg5 离子碰撞激发的碰撞强度.所有的跃迁均限定在主量子数为2的态之间.计算结果与用相对论扭曲波方法得到的结果进行了比较,R-matrix方法所得的结果更好.文中列出了部分光允许跃迁的数据,可以看出,R-matrix方法更适合计算低能碰撞.     

分子H_2X(X=O、S、Se)的全对称群Dirac理论研究

本文应用全对称群的Dirac理论计算了分子H_2X(X=O、S、Se)的结构,并与非相对论的结果比较.对比相对论和非相对论的结果,所得到的分子几何差异不大;而所计算的能量,相对论的比非相对论的要低,并能量随质量增加而降低;相对论值的极化率(A~3)和偶极矩更接近实验值.分子的电性状态为费密子共群的不可约表示E_1,明显地体现不可约表示E1的效应.所以,特别对重元素分子,更要应用相对论方法.     

碳原子1s~22s~22pns~3P态的能量和波函数

提出了构造碳原子1s~22s~22pns~3P态波函数的新方法,以Rayleigh-Ritz变分法为基础开发了一套计算碳原子1s~22s2~2pns~3P态波函数和能量的Mathemtica程序,具体计算了碳原子1s~22s~22pns~3P(n=3～6)态的波函数和非相对论能量及其相对论修正值(包括质量修正、单体达尔文修正、双体达尔文修正、自旋-自旋接触相互作用修正),计算结果与实验值非常接近.     

类锂离子内壳激发1s2s2 2S态的电离势和Auger跃迁率

采用鞍点变分方法和鞍点复数转动方法,并考虑相对论修正、质量极化效应,计算了类锂等电子系列(Z=10～20) 1s2s2 2S态的电离势、Auger跃迁率和辐射跃迁率.同时还计算了QED效应和高阶相对论修正对电离势的贡献.     

钠原子主线系精细结构的多体微扰计算

在相对论的框架下采用多体微扰理论(MBPT)方法计算了纳原子 np(n=3—9)态的能级精细结构分裂值. 为避免多体微扰计算中需要计算大量连续态的困扰, 通过引入外势的方法可以构建离散、有限和近似完备的数值基函数. 经求解相对论Hartree-Fock (RHF)方程及外势作用下的RHF方程可获得零级近似波函数和能级值. 为了使微扰展开能够收敛, 计算中用到了轨道角量子数l≤ 6的在一定能量分布范围内的中间态, 其中以在外势作用下的收缩态为主. 依此方法计算了纳原子主线系系列能级二阶微扰修正值, 同时还考虑了Breit效应的一级微扰修正对精细结构的影响. 通过与其他理论计算结果比较可看出, 本文计算结果在较大程度上更接近于实验值.     

类铍离子内壳激发态1s2p33Po的俄歇宽度、俄歇分支率和辐射跃迁率计算

采用鞍点变分方法和鞍点复数转动方法,并考虑相对论修正和质量极化效应,计算了类铍内壳激发态1s2p33Po的俄歇宽度、俄歇电子能量和俄歇分支率.同时还对1s2p33Po态到1s22p3p3Pe态(Z=4～10)的振子强度和辐射跃迁率进行了计算.计算结果和其他理论结果和实验数据符合的很好.     

Mechanism of laser-induced plasma shock wave evolution in air

A theoretical model is proposed to describe the mechanism of laser-induced plasma shock wave evolution in air. To verify the validity of the theoretical model, an optical beam deflection technique is employed to track the plasma shock wave evolution process. The theoretical model and the experimental signals are found to be in good agreement with each other. It is shown that the laser-induced plasma shock wave undergoes formation, increase and decay processes; the increase and the decay processes of the laser-induced plasma shock wave result from the overlapping of the compression wave and the rarefaction wave, respectively. In addition, the laser-induced plasma shock wave speed and pressure distributions, both a function of distance, are presented.     

Nonlinear excitation and stability analysis of ion-acoustic waves in a magnetized quantum plasma with exchange-correlation effects of degenerate electrons

The nonlinear ion-acoustic wave excitation and its stability analysis are investigated in a magnetized quantum plasma with exchange-correlation and Bohm diffraction effects of degenerate electrons in the model. Using reductive perturbation technique, the Zakharov-Kuznetsov (ZK) equation is derived for two dimensional propagation of ion-acoustic wave in a magnetized quantum plasma. It is found that the phase speed, amplitude and width of the nonlinear ion-acoustic wave structures are affected in the presence of exchange-correlation potential in the model. The stability analysis of the 2D ion-acoustic wave pulse is also presented. It is found that growth rate of the first and second order instabilities of 2D ion acoustic wave soliton is enhanced with the inclusion of exchange-correlation potential effect in the model.     

多孔介质BISQ模型中的慢纵波

着重研究了多孔介质BISQ模型中慢纵波的基本特性.给出了BISQ模型下慢纵波速度 和衰减的低频近似公式.与Biot理论对比，BISQ模型中慢纵波的衰减随频率降低急剧增大， 且随喷射流长度的减小而增加；相速度随喷射流长度的减小而增加，其低频极限值不是零； 孔隙流体位移与固相骨架位移之比的幅值随喷射流长度的增加而减小，其相位特点与Biot模 型预测的不同；在流体与孔隙介质的边界上可产生更大的渗流.为对比，同时也给出快纵波 的行为.依据BISQ模型可推断：非黏滞流体饱和孔隙介质中不存在喷射流机理；BISQ模型中 关键词： 多孔介质 喷射流 慢纵波 动力协调     

翼片加载螺旋线慢波结构的螺旋带模型

 翼片加载螺旋线慢波结构广泛应用于大功率、宽频带行波管中。建立了翼片加载螺旋线慢波结构的螺旋带模型，得到了实用的色散方程、耦合阻抗和衰减常数的表达式。利用导出的方程对实际行波管的螺旋慢波结构进行计算，并与测量结果和导电面模型进行了比较，计算结果与测量结果具有良好的一致性。分析了不同管壳半径对色散特性的影响。     

Wave number-frequency spectrum of turbulent pressure fluctuations: Methods of measurement and results

The methods proposed earlier for measuring the wave number-frequency spectrum of wall pressure fluctuations beneath a turbulent boundary layer are considered: the spatial filtering of the pressure field components by special-purpose transducers (wave filters) and the digital processing of signals obtained from an array of transducers. It is shown that, for the wave filters, transducers with a rectangular shape of sensitive surface rather than those with a circular one are necessary. Results of measuring the wave number-frequency spectrum of turbulent pressure fluctuations in a low-noise wind tunnel are presented. The measurements are performed with the use of four wave filters consisting of rectangular transducers with a constant sensitivity distribution over their surfaces. The mathematical model of the wave number-frequency spectrum proposed earlier by the authors is compared with the measurement data reported by Abraham and Keith. The model is used for processing the results of measurements in the wind tunnel. The measured spectra are compared with the data obtained by Martin and Leehey.     

Acoustic waves in a Cattaneo-Christov gas

A model is presented for an inviscid fluid using the recently proposed model for heat waves due to C. Christov. Christov's model generalizes the classical model of Cattaneo to the important case of a moving body. We here couple this to the equations of motion for a fluid. It is then shown that an acoustic wave will propagate together with a thermal wave. The theory allows for the possibility of a transverse wave in the heat flux. The wavespeeds are calculated exactly and one may fully determine the wave amplitudes.     

Extreme wave formation in unidirectional sea due to stochastic wave phase dynamics

The authors consider a stochastic model based on the interaction and phase coupling amongst wave components that are modified envelope soliton solutions to the nonlinear Schrödinger equation. A probabilistic study is carried out and the resulting findings are compared with ocean wave field observations and laboratory experimental results. The wave height probability distribution obtained from the model is found to match well with prior data in the large wave height region. From the eigenvalue spectrum obtained through the Inverse Scattering Transform, it is revealed that the deep-water wave groups move at a speed different from the linear group speed, which justifies the inclusion of phase correction to the envelope solitary wave components. It is determined that phase synchronization amongst elementary solitary wave components can be critical for the formation of extreme waves in unidirectional sea states.     

热质的运动与传递-热波

根据爱因斯坦狭义相对论,热量具有其对应的相对论质量,并且引入了描述热质(热量)运动的连续方程、动量方程.本文根据热质(热量)运动控制方程组,导出了热质(热量)的波动方程,证明了热量具有波动的传递方式,当热质动能与热质的耗散在同一量级时,得到了有限的热波传播速度.分析了热波产生的物理机制.基于热质理论的热波模型与CV模型进行了比较,指出了CV模型在物理上的缺陷.最后对一维热波的传播过程进行了数值模拟,给出了超快速导热过程的物理图像.     

Wave front interaction model of stabilized propagating wave segments

A wave front interaction model is developed to describe the relationship between excitability and the size and shape of stabilized wave segments in a broad class of weakly excitable media. These wave segments of finite size are unstable but can be stabilized by feedback to the medium excitability; they define a separatrix between spiral wave behavior and contracting wave segments. Unbounded wave segments (critical fingers) lie on the asymptote of this separatrix, defining the boundary between excitable and subexcitable media. The model predictions are compared with results from numerical simulations.