Magnetic,structural and electrical properties of ordered and disordered Co50Fe50 films

Co₅₀Fe₅₀ films with thickness varying from 100 to 500 Å were deposited on a glass substrate by sputtering process, respectively. Two kinds of CoFe films were studied: one was the as-deposited film, and the other the annealed film. The annealing procedure was to keep the films at 400 °C for 5 h in a vacuum of 5×10⁻⁶ mbar. From the X-ray study, we find that the as-deposited film prefers the CoFe(1 1 0) orientation. Moreover, the body-centered cubic (bcc) CoFe(1 1 0) line is split into two peaks: one corresponding to the ordered body-centered tetragonal (bct) phase, and the other, the disordered bcc phase. After annealing, the peak intensity of the ordered bct phase becomes much stronger, while that of the disordered bcc phase disappears. The annealing has also caused the ordered CoFe(2 0 0) line to appear. When the amount of the ordered bct phase in Co₅₀Fe₅₀ is increased, the saturation magnetization (M_s) and coercivity (H_c) become larger, but the electrical resistivity (ρ) decreases. From the temperature coefficient of resistance (TCR) measurement, we learn that the bct grains in the CoFe film start to grow at temperature 82 °C.     

Anionic polymerization of star-shaped nylon 6 with a trifunctional initiator

The anionic polymerization of ?-caprolactam (CLM) has been shown to proceed at high reaction rate when catalyzed by metallic lactamates and initiated by acyllactams. The role of initiator and catalyst concentration on the process of ?-caprolactam anionic polymerization has been explored, with the aim of selecting the most suitable experimental conditions for reaction injection molding (RIM). The overall polymerization rates and physical properties for reaction injection molding of star-shaped nylon 6 homopolymer have been studied by the quasi-adiabatic process. In order to model the actual rapid molding conditions, time vs. temperature reaction profiles were measured, and the relative rates of polymerization subsequently determined from these data.     

Allocating unfunded liability in pension valuation under uncertainty

This paper studied the cost allocation for the unfunded liability in a defined benefit pension scheme incorporating the stochastic phenomenon of its returns. In the recent literature represented by Cairns and Parker [Insurance: Mathematics and Economics 21 (1997) 43], Haberman [Insurance: Mathematics and Economics 11 (1992) 179; Insurance: Mathematics and Economics 13 (1993) 45; Insurance: Mathematics and Economics 14 (1994) 219; Insurance: Mathematics and Economics 14 (1997) 127], Owadally and Haberman [North American Actuarial Journal 3 (1999) 105], the fund level is modeled based on the plan dynamics and the returns are generated through several stochastic processes to reflect the current realistic economic perspective to see how the contribution changed as the cost allocation period increased. In this study, we generalize the previous constant value assumption in cost amortization by modeling the returns and valuation rates simultaneously. Taylor series expansion is employed to approximate the unconditional and conditional moments of the plan contribution and fund level. Hence the stability of the plan contribution and the fund size under different allocation periods could be estimated, which provide valuable information adding to the previous works.     

单链表在离子发动机光学系统粒子模拟中的应用

 目前离子发动机光学系统数值模拟大多采用PIC方法，由于该方法需要跟踪单个粒子的运动，因此需要存储每个粒子的位置信息与运动信息。传统的粒子模拟程序中，保存粒子信息大多采用数组的方式，但是采用这种方式存在弊端，例如对粒子总数变化的自适应不好。基于此开发了一种使用链式存储结构的粒子模拟程序，该程序使用带头节点的单向链表存储粒子信息。使用基于链式存储结构的PIC方法对离子发动机光学系统进行了粒子模拟，验证了链式粒子信息存储方法在粒子模拟中的可用性。模拟表明：（1）在粒子模拟中采用链式存储结构存储粒子信息，无需预先指定最大粒子总数，程序可自适应粒子总数的变化，因此无需进行试算，节省了计算时间；（2）在粒子模拟中采用链式存储结构，由于不存在内存资源的浪费，因而可显著提高程序的存储效率与计算效率。     

Photoinduced Transformation between Charge Carrier and Spin Carrier in Polymers

By dynamical simulations, we show a transforming process between neutral soliton （spin carrier） and charged soliton （charge carrier） in polymers via photo-excitation, taking a polaron as the transitional bridge. It is photoinduced transformation between spin carrier and charge carrier. In this way, we demonstrate an access for polymers to be applied to spintronics.     

Anchoring Properties of Nematic Liquid Crystals Studied Using the Attenuated Total Reflection Method

By using the attenuated total reflection method associated with the excitation of surface plasmons, the tilt angle of the liquid crystal director and its gradient at the surface are measured in a planar nematic cell as a function of the applied voltage. The surface anchoring anisotropy δπ of the liquid crystal and the surface elastic constant k_s, are found to be δπ = 0.288 erg/cm and k_s, = 9·12 × 10^-11 erg, respectively, when the boundary condition suggested by Barbero et al is used. The theoretical and experimental values obtained with this boundary condition and that of Mada are discussed. The results show that the boundary condition proposed by Barbero et al is in better agreement with the experiment.     

铟封前后透射式GaAs光电阴极光谱响应特性的测试与分析

利用自行研制的光谱响应测试仪工程化样机,对透射式GaAs光电阴极在高温激活结束、低温激活结束以及铟封成管后的光谱响应特性进行了测试。结果显示,铟封后阴极整个响应波段的光谱响应下降,长波响应受到最显著的影响,表现为800~815 nm之间长波响应大幅度衰减,截止波长和峰值波长向短波移动,峰值响应和积分灵敏度减小,最终的光谱响应曲线变得平坦。阴极参量的计算结果反映铟封后阴极的表面逸出几率降低,说明铟封引起阴极表面激活层发生变化,使得能量较低的长波段光生电子不容易逸出,阴极长波响应和灵敏度随之降低。进一步分析了铟封过程中影响阴极表面激活层的因素。     

Sagnac棱镜角公差与干涉光谱仪光谱分辨率的关系分析

根据干涉成像光谱仪光谱分辨率对角向差的要求，通过对实体Sagnac干涉仪结构和光路进行分析，从三个相互垂直的方向出发，研究了光谱分辨率和棱镜角公差之间存在的关系；并推导了满足光谱仪光谱分辨率要求的实体Sagnac干涉棱镜的角公差公式；用实例说明了关系式的应用方法，如果不考虑棱镜变形引起的色散及棱镜的面型误差和付氏镜的残余像差的影响,而只考虑棱镜的角误差对光谱分辨率的影响,则通常情况下干涉棱镜的角公差要求较严，约20″以内.     

基于支持向量机的肤色滤波器

为了探测图像中的肤色像素，提出了一种新的方法-支持向量机（SVM：Support Vector Machine）方法.它是一种基于肤色的非特定人的面部定位方法，是非接触人机交互技术和机器视觉中的一个重要内容.实验结果表明，采用支持向量机方法较传统人工神经网络方法不仅有更高的探测准确性，而且具有更好的推广性能.由于SVM采用结构风险最小化（SRM：Structural Risk Minimization）准则，在最小化训练误差（经验风险）的同时，尽量缩小模型预测误差的上界，从而使模型有更好的泛化能力.