The effect of improved satellite line shapes on the argon Heβ spectral feature

The effect of the interference term in the electron broadening of the Li-like satellites to the Ar Heβ line has been investigated in the standard Stark broadening theory. Although the interference term has negligible or small effect on satellite lines with spectator electrons in n = 2 and n = 3 shells, it shows significant narrowing for lines with n = 4 spectator electrons. Nevertheless, the improved n = 4 satellite line shape makes a small difference in the emergent intensity distribution of the composite spectral feature. Accordingly, this change in line shape does not affect previous diagnosis of plasma conditions in Ar-doped ICF implosion cores.     

Frequency dependent electron collisional widths for opacity calculations

It is shown that theoretical Rosseland mean opacities are sensitive to spectral line shape models. Due to computational constraints, however, opacity codes typically use Voigt or Lorentz profiles. Both of these profiles have an incorrect far wing behavior that can significantly overestimate the photon absorption. A new line profile is proposed, based on second-order line broadening theory, which is both more physical and relatively fast to compute.     

Collision operators for Stark line shapes: When does the unified theory fail?

It is shown that the unified theory for Stark broadening leads to incorrect results when correlated emitter–perturber collisions are present. With a kinetic theory treatment, we propose an extension of the model able to account for such correlations. The treatment presents analogies with renormalization techniques and the resulting collision operator has a structure similar to that obtained within the unified theory. We illustrate the applicability of the model through calculations of hydrogen line shapes in ideal cases.     

Electron broadening of isolated lines with stationary non-equilibrium level populations

It is shown that a quantum kinetic theory approach to line broadening, extended to stationary non-equilibrium states, yields corrections to the standard electron impact widths of isolated lines that depend on the population of the radiator internal levels. A consistent classical limit from a general quantum treatment of the perturbing electrons also introduces corrections to the isolated line widths. Both effects are essential in preserving detailed-balance relations. Preliminary analysis indicates that these corrections may resolve existing discrepancies between theoretical and experimental widths of isolated lines. An experimental test of the results is proposed.     

Overview of plasma line broadening

We review the basics of line broadening, its relation to fluctuations and disorder, what causes broadening, the memory loss mechanism and the Standard Theory of line broadening developed by H.R. Griem and others from a modern viewpoint. This modern view benefits from many years of progress and includes a coherent theoretical perspective without the need for a conceptually different view of electrons and ions. Both electrons and ions are described in terms of their random fields. This modern and unified view allows, among other things, extending the range of validity of line profile calculations to complex situations.     

三维计算断裂力学

断裂力学理论从1921年Griffith研究玻璃的脆性断裂问题开始,经历了从线弹性体系到弹塑性以及蠕变理论体系、从单参数到多参数体系和从理想的二维平面理论到实际三维含裂纹结构的三维断裂理论的发展历程。针对应力强度因子K和J积分以及C(t)积分的计算方法从理想化模型的理论计算发展到实际复杂工程结构裂纹体计算的各种商业软件平台以及专业的断裂理论分析平台。尤其是随着计算机技术的发展,对三维含裂结构的静态和扩展裂纹的计算模拟已经能够融入计算机辅助设计。结合本研究组近30年来在三维疲劳断裂理论和应用研究方面的体会,简述了三维计算断裂力学从裂纹体应力应变分析和断裂参数计算到三维蠕变断裂和疲劳裂纹扩展模拟的国内外进展,并对涉及的计算方法,包括原子尺度和跨尺度的计算模拟,以及目前面临的挑战性问题作了简要介绍和分析。     

Scaling of hydrogen electron stark widths at high densities and theInglis–Teller limit

The density dependence of Stark widths at high densities can vary significantly and in a manner contrary to the well-known behavior at lower densities, reflecting issues such as the screening length, collisions, and non-impact effects. In this regime reversed temperature dependence as well as a weak density dependence is possible. At high densities effects such as continuum lowering and the Inglis–Teller limit, whose computation needs care, become important. Specifically the atomic wavefunctions involved may be: a) broadened mostly or significantly by electron collisions; b) such that practically all collisions are strong so that standard perturbative estimates do not work; or c) comparable to the screening length, so that the penetrating collisions are severely overestimated by the standard line broadening theory. Interesting possibilities are a width saturation, the experimental determination of the shielding length from the line widths and abnormal continuum lowering behavior.     

Defects in gradient micropolar elasticity—II: edge dislocation and wedge disclination

A theory of gradient micropolar elasticity based on first gradients of distortion and bend-twist tensors for an isotropic micropolar medium has been proposed in Part I of this paper. Gradient micropolar elasticity is an extension of micropolar elasticity such that in addition to double stresses double couple stresses also appear. The strain energy depends on the micropolar distortion and bend-twist terms as well as on distortion and bend-twist gradients. We use a version of this gradient theory which can be connected to Eringen's nonlocal micropolar elasticity. The theory is used to study a straight-edge dislocation and a straight-wedge disclination. As one important result, we obtained nonsingular expressions for the force and couple stresses. For the edge dislocation the components of the force stress have extremum values near the dislocation line and those of the couple stress have extremum values at the dislocation line and for the wedge disclination the components of the force stress have extremum values at the disclination line and those of the couple stress have extremum values near the disclination line.     

THE PRECISE AND NEW ANALYSIS FOR A MODE Ⅲ GROWING CRACK IN AN ELASTIC-PERFECTLY PLASTIC SOLID

The near crack line field analysis method has been used to investigate into ModeⅢ quasistatically propagating crack in an elastic-perfectly plastic material.Thesignificance of this paper is that the usual small scale yielding theory has been brokenthrough.By obtaining the general solutions of the stresses and the displacement rate ofthe near crack line plastic region,and by matching the general solutions with theprecise elastic fields(not the usual elastic K-dominant fields)at the elastic-plasticboundary,the precise and new solutions of the stress and deformation fields,the sizeof the plastic region and the unit normal vector of the elastic-plastic boundary havebeen obtained near the crack line.The solutions of this paper are sufficiently precisenear the crack line region because the roughly qualitative assumptions of the smallscale yielding theory have not been used and no other roughly qualitative assumptionshave been taken,either.The analysis of this paper shows that the assumingly“steady-state cas     

Line profiles of Ni-like collisional XUV laser amplifiers: Particle correlation effects

We present a detailed analysis of the different processes that contribute to the spectral broadening of the Ni-like Ag XUV laser line, including the effects of particle correlations on the broadening due to the radiator motion (Doppler broadening). We consider two different regimes of collisional excitation pumping: the transient pumping for which the ionic temperature is relatively low and the plasma coupling parameter is large, and the quasi steady-state pumping for which the ionic temperature is higher and the plasma coupling parameter is of the order of 1. In both cases, by using classical molecular dynamics simulation techniques, we show that ionic correlations actually modify the radiator-motion broadened profiles and cannot be neglected in evaluating the Doppler effect. The subsequent narrowing of the Doppler component is small compared to the overall linewidth, which includes the effect of homogeneous collisional broadening. However, ionic correlations will also affect the amplification of the lasing line, especially when the laser enters the saturation regime, because it will lead to a homogenization of the spectral profile.     

A model for computer-based data acquisition and control

This paper describes the theory and ongoing development of a computer-based system for data acquisition and control termed theVIrtualDataAcquisition andControl (VIDAC) system. The VIDAC system has particular application to laboratory experimental research and is currently applied to the field of materials testing. A model is presented and intended to display the basic similarities of data-acquisition algorithms and forms the conceptual basis for the VIDAC system. A discussion of the implementation of this model in computer software is given and two experimental programs in materials testing are described which have used the VIDAC ideology.     

A finite element solution of unsteady two-dimensional flow in cascades

A theory is presented for unsteady two-dimensional potential transonic flow in cascades of compressor and turbine blades using a mesh of triangular finite elements. The theory leads to a computer program, FINSUP, which is fast and has moderate storage requirements, so that it can be run on a personal computer. Comparisons with other theories in special cases show that the program is accurate in subsonic flow, and that in supersonic flow, although the wave effects are smeared by the numerical process, the results for overall blade force and moment have acceptable accuracy. The program is useful for engineering assessment of unstalled flutter of actual compressor and turbine blades.     

在工程流体力学教学中引入CFD工程案例的探讨

在长期的工程流体力学教学过程中,发现学生对这门课普遍存在畏难情绪,对复杂的理论知识掌握困难.考虑到工程流体力学的研究方法分为理论分析方法,实验方法和数值方法,而其中数值方法在传统教学中应用的较少,所以试图通过适当增加数值方法的应用来改善教学效果.随着本科生对计算机应用能力的增强以及知识面的逐渐扩展,本文提出增加结合专业背景,理论知识及软件应用的综合案例以满足当前课程及学生发展的需求.     

非局部弹性理论概述及在当代材料背景下的一些进展

局部作用原理在发展经典连续介质力学的本构关系中起着重要的作用，由此导出的简单物质理论得到了广泛的应用．然而，随着科技的发展，各种具有微结构的新材料不断涌现，理论和实验表明，非局部理论可以更好地刻画这些材料的宏观力学行为．本文简要介绍了一些传统的非局部弹性理论，包括Eringen 理论、Kunin 理论、Mindlin 理论；阐述了针对复合材料发展的，具有时间-空间非局部特征的Willis 方程、最新的时间-空间耦合非局部弹性动力学理论以及近场动力学理论．时间-空间非局部理论反映了复合材料宏观性能固有的非局部特征，而具有空间非局部特征的近场动力学理论便于处理具有不连续性的问题．最后，本文讨论了非局部理论的发展中值得关注的一些问题.     

常航速船波势及船波阻力的边界元法

利用满足Laplace方程,线性化自由面条件及无穷远处条件的Havelock兴波源涵数,建立了关于常航速稳态船波势函数的边界积分方程.针对这个积分方程,建立了相应的数值计算方法,编制了一般三维问题的边界元法计算机程序,可用来计算全潜和半潜物体的稳态绕流场及船舶兴波阻力.     

Turbulence and line shape formation in plasmas

We investigate the role of turbulent fluctuations on line shape formation in optically thin plasmas. A general expression, valid if the turbulent scales are much larger than the atomic scales, is obtained for the profile measured using a passive spectroscopy set up. Well-known limiting cases for Doppler and Stark broadening are identified. Then, the role of temperature fluctuations on Doppler line shapes, and the effect of density fluctuations on Stark broadened lines in the quasi-static regime are investigated.     

X-ray line emissions from tamped thin aluminum targets driven by subpicosecond-duration laser pulses

We report on atomic kinetics and X-ray line spectra modeling work of plasmas generated by high-intensity, ultrashort-duration pulsed lasers. Our work is motivated by the need to analyze and interpret experiments with laser-irradiated layered targets performed at the Max-Planck-Institut für Quantenoptik. The focus of this Paper is on the theoretical characterization of the properties of X-ray line emissions as signatures of plasma conditions. Our model considers several spectral features with detailed attention paid to atomic kinetics, intrinsic spectral lineshapes in a high-density plasma environment (in particular Stark broadening and line shift effects), and spectroscopic-quality radiation transport (opacity effects). We apply our model to the analysis of time-integrated K-shell aluminum X-ray line spectra and time-resolved total line intensities obtained from the layered targets. Modeling calculations indicate that red line shifts observed in these experiments cannot be explained by shifts in the centers of gravity of composite spectral features due to blending with enhanced satellite contributions, but are consistent with intrinsic line shift effects in both resonance and satellite lines. We also investigate the sensitivity of our results to the selection of one of three adopted models for laser-energy deposition and transport within the target.     

NEAR CRACK LINE ELASTIC－PLASTIC ANALYSIS FOR A CRACK LOADED BY ANTIPLANE POINT FORCES

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注塑模冷却系统灵敏度分析方法及应用

本文提出了利用灵敏度数值计算方法进行设计参数选择和修改的注塑模冷却系统设计方法和理论分析数学模型,并开发出了一个处于CAD环境中的冷却系统分析软件,为设计人员优化冷却管道布置、保证模具型腔表面温度分布均匀、减少塑件翘曲变形提供了科学依据和分析手段。