虚阴极振荡在谐振腔中激励微波的理论分析

文中将虚阴极看作一个带电圆盘，用场的模式展开方法讨论了虚阴极振荡在谱振腔中对微波的激励，得到了微波频率、模式与虚阴极振荡的关系。结果表明，在谐振腔较长时容易得到单一频率成分微波，这与试验结果一致。分析还表明，特征频率越接近虚阴极振荡频率的模式，其展开系数就越大。     

均匀磁场中二维电子量子电流的期待值

本文利用Landau波函数及广义Lagurre多项式,计算了均匀磁场中电子运动的量子电流的期待值。     

等淬球铁中残留奥氏体的磁性测量

球铁在380℃等温处理后淬水测量其磁性以估计残留奥氏体含量,测量结果与用X光衍射物相分析及热染法相比较发现奥氏体含量相差30%。分析这一系统误差产生原因,讨论磁性法的使用条件。     

3d过渡金属掺杂GaAs的居里温度研究

本文用Zener模型对GaAs掺杂3d过渡金属（TM=Sc,Ti,V,Cr,Mn,Fe,Co,Ni）的居里温度进行理论计算.文中详细介绍了GaAs材料的晶体结构和基本参数;推导了计算居里温度的函数表达式;并计算了不同元素在不同掺杂浓度下的居里温度值,通过计算得到如下结论：3d过渡金属取代Ga位置时,掺杂Cr和Mn时居里温度较高,可以实现室温铁磁性,掺杂其余元素时居里温度很低;3d过渡金属取代As位置时除了掺杂V和Ni居里温度很低以外,其余均可获得室温铁磁性;取代As位置时合成的DMS材料的居里温度普遍高于取代Ga位置时的居里温度.     

Absence behaviour,turnover and disability: A study among city bus drivers in the Netherlands

Abstract

Absenteeism, turnover and disability, and relationships between them have been studied among city bus drivers in the Netherlands. The theoretical framework for the study was a cumulative process model of work and health. Absenteeism among these drivers was two to three times as high as the national average, while the risk of disablement was more than twice as high as the risk for male Dutch civil servants in general. Bus drivers who had to leave their job for medical reasons did so at a younger age than other groups of civil servants. The main conditions leading to disablement related to the back, tendons and joints (35%), mental disorders (35%) and cardiovascular diseases (12%). It was shown that long-term absenteeism is a strong precursor of future disability. The research suggests a work-related process of progressive deterioration of health and well-being over a reasonably long period of time. Driving city buses seems to be an occupation with high risks for health and well-being.     

Nonlinear voxel-based modelling of the haemodynamic response in fMRI

A common assumption for data analysis in functional magnetic resonance imaging is that the response signal can be modelled as the convolution of a haemodynamic response (HDR) kernel with a stimulus reference function. Early approaches modelled spatially constant HDR kernels, but more recently spatially varying models have been proposed. However, convolution limits the flexibility of these models and their ability to capture spatial variation. Here, a range of (nonlinear) parametric curves are fitted by least squares minimisation directly to individual voxel HDRs (i.e., without using convolution). A ‘constrained gamma curve’ is proposed as an efficient form for fitting the HDR at each individual voxel. This curve allows for spatial variation in the delay of the HDR, but places a global constraint on the temporal spread. The approach of directly fitting individual parameters of HDR shape is demonstrated to lead to an improved fit of response estimates.     

纳米磁性液体的分散稳定性分析

从纳米磁性液体中磁性颗粒的沉淀和团聚的角度分析了磁性液体稳定分散的条件，讨论了在外场下磁性颗粒的尺寸对其沉淀的影响，并引入势能的概念定量研究了决定磁性颗粒团聚体形成的3种主要作用力。利用数值计算的方法，讨论了3种相互作用势能以及净势能与磁性颗粒间表面间距和表面活性剂层厚度的关系。结果表明，增大表面活性剂层的厚度是避免磁性颗粒团聚体形成的关键措施。     

基于驱动要素四维构成的顾客资产提升策略

顾客作为现代企业最重要的稀缺性资源,越来越得到企业的关注,企业将其作为一种竞争性的战略资产而加以管理并努力使顾客资产获得提升。在分析和阐述传统的顾客资产驱动要素三维构成模型的基础上,从信息技术飞速发展和企业多元化经营的实际出发,详细阐述了改进传统驱动要素构成模型的原因,在此基础上,对传统模型进行了改进,构建了顾客资产驱动要素的四维构成模型,引入了由口碑宣传和交叉购买构成的感知驱动要素,并结合中国的文化环境对顾客资产的各亚驱动要素进行了简要诠释。然后根据顾客金字塔模型对不同层级顾客特征的差异分析,从价值驱动、品牌驱动、关系驱动以及感知驱动等顾客资产驱动要素入手,提出了不同层级顾客资产提升的具体策略。     

模拟复合正交神经网络在轴向磁轴承中的控制研究

在数字复合正交神经网络(NN)的基础上提出一种模拟复合正交神经网络,并用于轴向磁轴承的控制中.控制器采用模拟复合正交神经网络与PID的并行控制方法,对带有负载干扰的轴向磁轴承控制系统作了PID控制与NN PID控制的仿真实验.仿真结果表明,相对于常规PID控制器,该并行控制法具有非常好的抗干扰与自适应能力,获得了满意的控制效果.     

退火对软磁合金的最大磁导率影响的机理研究

本文以Fe－Ni软磁合金为研究对象，从晶体缺陷及内应力两方面分析了退火参数对最大磁导率影响的机理，指出位错、晶界以及晶格畸变应力是影响最大磁导率的主要因素。