高维非光滑动力系统的周期响应数值分析

本文研究以复杂弹塑性结构，含间隙或干摩擦的机械等为背景的高维非光滑动力系统周期响应的数值解法。提出了一种对短时间历程动响应进行曲线拟合后外推周期响应的迭代格式，改变了现有方法未充分利用动力系统内在特性及中间计算结果所含信息的不足，使计算效率有了阶次性的提高且收敛性能亦大为改善。     

A new spline approach for data fitting

This paper presents an extension of the Modified Spline Technique (MST) formulation for data fitting named power spline, which gives consistent results for sets of data of concave and convex curves. This method is based on a technique which couples an implicit formulation of the maximum likelihood principle to the spline method, making the method suitable to fit data when no physical model is available. The MST method proved to be better than to the spline method and the extended spline fit technique (EST), because it provided accurate results for the first and second derivatives in sets of data where the EST solution developed inaccuracies. The EST method is a formulation that couples Least Squares to the spline method. There are, however, some sets of data where the MST method would show inconsistent solutions for the first and second derivatives. The power spline method eliminates these problems for concave or convex curves. Another improvement on the method is a more flexible choice for the interval boundaries.¹     

Study on γ-ray exposure buildup factors and fast neutron-shielding properties of some building materials

We have computed γ-ray exposure buildup factors (EBF) of some building materials; glass, marble, flyash, cement, limestone, brick, plaster of paris (POP) and gypsum for energy 0.015–15 MeV up to 40 mfp (mfp, mean free path) penetration depth. Also, the macroscopic effective removal cross-sections (Σ_R) for fast neutron were calculated. We discussed the dependency of EBF values on photon energy, penetration depth and chemical elements. The half-value layer and kinetic energy per unit mass relative to air of building materials were calculated for assessment of shielding effectiveness. Shielding thicknesses for glass, marble, flyash, cement, limestone and gypsum plaster (or Plaster of Paris, POP) were found comparable with ordinary concrete. Among the studied materials limestone and POP showed superior shielding properties for γ-ray and neutron, respectively. Radiation safety inside houses, schools and primary health centers for sheltering and annual dose can be assessed by the determination of shielding parameters of common building materials.     

Photon attenuation coefficients of different rock samples using MCNPX,Geant4 simulation codes and experimental results: a comparison study

ABSTRACT

The photon attenuation coefficients for the rocks (Feldspathic basalt, Compact basalt, Volcanic rock, Pink granite, Sandstone and Dolerite) have been investigated using MCNPX and Geant4 codes for photon energies 122, 356, 511, 662, 1170, 1275 and 1330 keV. Comparison of the simulation and experimental results of mass attenuation coefficients is presented. The exposure buildup factors also have been calculated with the help of the G-P fitting method. The comparison showed reasonable agreement between the simulated and experimental data for all rocks. The results show that sandstone has the highest mean free path as well as exposure buildup factor which signifies that sandstone requires a larger thickness for protection from photons.     

高Z类钴Te25+离子3p63d9-3p53d10,3p63d9-3p63d84p跃迁及振子强度的计算

用多组态自洽场方法,结合我们提出的半经验拟合公式,计算了高Z类钴Te25+离子3p63d9-3p53d10,3p63d9-3p63d84p跃迁和振子强度,与实验符合得较好。     

掩埋隧道结垂直面激光器速率方程参量提取

为了设计和优化高速激光二极管的高频特性,其速率方程模型参量的精确提取方法非常重要.本文针对新型长波长高带宽的掩埋隧道结垂直面激光器,给出一种速率方程模型参量提取方法.此方法是主要基于阈值电流、输出光功率、张弛振荡频率、阻尼因子和高偏置下增益压缩因子非线性效应等因素,根据已测量的不同偏置下芯片的小信号频率响应来拟合出方程中的张弛振荡频率和阻尼因子.通过考虑增益压缩因子,分别非线性拟合已提取的偏置光功率下的张弛振荡频率和阻尼因子,即可提取速率方程模型中的参量.     

基于LSSVM的色散曲线拟合

本文利用最小二乘支持向量机对三棱镜色散实验数据进行拟合,结果表明在小样本数据的情况下,支持向量机拟合比多项式拟合的效果好.     

Raman comparison of skin dermis of different ages: focus on spectral markers of collagen hydration

Skin aging is the most visible sign of aging of the body. This complex process involves molecular and structural alterations of the main skin constituents. The major cutaneous constituent is type I collagen that gives strength and resilience to the skin. This macromolecule possesses a particular triple helix structure and is arranged in the form of a fibrous network. Water plays a crucial role for maintaining this molecular assembly which is altered during intrinsic chronological aging. To investigate some of these structural alterations, Raman microspectroscopy was employed since this biophotonic approach permits to probe the biomolecular composition of the skin in a non‐destructive manner. In addition, type I collagen gives specific Raman vibrations; some of which being sensitive to the molecule conformation and to the water environment. In this purpose, Raman spectra of four skin samples of different ages (two samples of 40 year old and two samples of 70 year old) were collected by varying the relative environmental humidity. Our experiments highlighted spectral differences between the four samples. The analysis of the Raman data permitted to suggest a model for the interactions between collagen and water molecules and a decrease in collagen fibers compactness with chronological aging. Our study demonstrates that Raman spectroscopy can be a useful tool to investigate skin aging, with innovative applications in dermatology as well as in cosmetics. Copyright © 2013 John Wiley & Sons, Ltd.     

确定离子交换平面波导折射率分布的预测-校验法

提出一种基于反WKB法与分段线性插值的最小二乘拟合方法(即预测-校验方法)来确定离子交换玻璃波导的横向折射率分布,它将反WKB法与分段线性插值所计算出的结果作为近似值(预测),然后进行最小二乘拟合(校验),并与基于反WKB的分段线性插值方法进行比较.数值计算表明,这一算法能有效地重建渐变离子交换平面波导的横向折射率分布.     

径向剪切干涉图处理

提出一种径向剪切干涉图的处理方法,利用最小二乘法以一定义在单位圆上的完全正交的Zernike多项式系列来直接拟合波面。用这种方法可以得出波面函数,从而计算出波面上任一点的波差值。