决策系统属性约简的双向算法

提出了决策系统中对象约简的新思想,即在搜索属性约简的同时不断地缩小论域;并设计了一个采用增量式方法计算决策系统的双向约简算法;分析了算法的时间复杂度,最后用一个实例说明了算法的可行性与有效性.     

Matching by solenoids in space charge dominated LEBTs

The betatron matching of a rotationally asymmetric beam in space charge dominated low-energy beam transports （LEBTs） where solenoids are used for the transverse matching has been studied. For better understanding, the coupling elements of a beam matrix are interpreted in special forms that are products of a term defined by the Larmor rotation angle and another by the difference between the beam matrix elements in the two transverse planes. The coupling form originally derived from the rotationally symmetric field in solenoids still holds when taking into account the rotationally asymmetric space charge forces that are due to the unequal emittance in the two transverse planes. It is shown in this paper that when an LEBT mainly comprising solenoids transports a beam having unequal emittance in the two transverse planes and the linear space charge force is taken into account, the initial Twiss parameters can be modified to obtain the minimum and equal emittance at the LEBT exit. The TRACE3D calculations also prove the principle. However, when quadrupoles that are also rotationally asymmetric are involved in between solenoids, the coupling between the two transverse planes becomes more complicated and the emittance increase is usually unavoidable. A matching example using the CSNS （China Spallation Neutron Source） LEBT conditions is also presented.     

Lie algebraic analysis for the nonlinear transportof intense pulsed beams in electrostatics lenses

The Lie algebraic method is applied to the analysis of the nonlinear transport of an intense pulsed beam in cylindrically symmetrical electrostatic lenses, and particle orbits in a six-dimensional phase space (x, p_x, y, p_y, τ, p_τ) are obtained in the second order approximation. They can also be acquired in the third or higher order approximation if needed. In the analysis, we divide the electrostatic lenses into several segments. Each segment is considered as a uniform accelerating field, and each dividing point is treated as a thin lens. The particle distribution in a three-dimensional ellipsoid is of Gaussian type.     

拉曼光谱法在纸张分析中的应用

拉曼光谱法作为一种高效无损的分析方法,在纸张分析中得到了广泛的应用,本文概述了拉曼光谱法在纸张分析中的主要应用方向。     

静电分析器非线性轨迹的Lie代数分析

介绍了Lie代数的方法，用Lie代数方法分析了静电分析器对束流传输过程的非线性影响，其计算结果分析到三级近似. 首先给出了静电分析器的哈密顿函数，然后将哈密顿函数展开为齐次多项式的和，再求Lie映射，最后得到粒子轨迹各级近似解.     

水面式弧形闸门静水总压力值的计算

我国过去一直沿用格里申的计算弧形闸门静水总压力值的方法。本文提出一个直接计算静水总压力值的方法。当水面式弧形闸门上下游同时有水时(图1),作用于闸门曲面板上的静水总压力,应根据弧形闸门曲面板上任一点的水深与弧长的关系,按如下定积分进行计算...     

磁控溅射多层沉积Nb_3Sn超导薄膜北大核心CSCD

Nb3Sn金属合金是一种性能优良的超导材料。磁控溅射多层沉积是用两个溅射源分层沉积铌和锡,再经过高温退火后获得超导薄膜的方法。用这种方法所获得的超导薄膜的原子组分的调整比较方便,对于Nb3Sn的研究较为有利。实验测量了样品的超导参数和晶格参数,其超导临界温度(Tc)可达17 K,剩余电阻率(RRR)为5左右。需要进一步研究相关工艺,以便提高RRR,从而使这种方法在超导加速腔的制造中得到应用。     

基于概念格的决策形式背景属性约简及规则提取

给出了决策形式背景下的属性约简与规则提取方法.为此,针对属性约简中起不同作用的属性,区分了必要属性与不必要属性,给出了各类属性的特征和判别方法;在此基础上得到了决策形式背景下的规则提取与属性约简方法,并通过实例表明了该约简方法的可行性与有效性.     

Intense beam nonlinear transport in solenoid lenses

Lie algebraic methods are used in the analysis of the nonlinear transport of charged particle beams in solenoid lenses. Space charge effects are included. The particle distribution we used is a K－V type. Similar procedures can also be used for magnetic dipoles, quadrupoles, sextupoles and other optic elements.     

网络形式背景下的知识流动方法研究

将形式背景与复杂网络分析结合,研究如何从网络节点之间的有向关系出发分析节点内涵属性之间的有向流动趋势。首先,定义知识流动算子和知识流动矩阵,研究有向对象之间的知识流动。其次,定义知识流动网络形式背景和知识流团,进一步研究网络中知识流团的网络特征值,用来描述网络中知识流团的平均影响力和影响力差异。另外,结合引文网络与标准加权直接引用(NWDC)方法构建知识流动矩阵和属性链接值,依次提出知识出入度矩阵构建算法、知识流动矩阵构建算法。针对链接值预测问题提出改进链路预测方法、链接值预测方法,并与6种ML算法结合应用于Web of Science核心期刊库下载的数据集中,结果表明这两种预测方法效果优于链路预测且链接值预测方法效果最好。最后,根据链接值预测方法预测冷热门知识,并由冷热门知识流团的网络特征值对该结果进行验证。