多信息输出位移传感器

本文提出一种用于空间自由曲面测量的多信息输出位移传感器.该传感器结构简单,传感器的输出量与被测量成线性关系,不但能给出位移信息、倾斜角度,还能给出测量光的强弱信息.     

完全可压缩渗流驱动问题的特征线有限元方法及其误差分析

多孔介质中渗流驱动问题数值方法的研究，对合理经济地开发油田，了解地下油水运动规律有一定意义。特征线法结合差分或有限元法解渗流问题，在理论和应用上获得了成功３－５，但还有很多问题需进一步研究２．前人研究多是假定流体不可压或微可压，本文研究一类完全可压缩两相驱动问题。采用特征线法与有限元法相结合，构造并分析了全离散数值格式，基于周期性假设，证明了最优Ｌ２模误差估计。     

Characteristics of vocal fold adduction related to voice onset

This study examined whether vocal fold kinematics prior to phonation differed between hard (glottal), normal, or breathy onsets in men and women. Glottal landmarks were identified and digitized from videotape recorded with a rigid laryngoscope during different voice onset types. Significant linear relationships (p 0.0055) were found among onset types on measures of (a) gesture duration when moving from 80% to 20% of maximum distance during adduction, (b) maximum velocity, (c) duration between the completion of adduction and phonation onset, and (d) ratios of maximum velocity to maximum distance between the vocal processes, an estimate of stiffness. The gesture duration was greatest for breathy onsets and least for hard onsets, while the maximum velocity, latency between adduction and phonation onset, and estimated stiffness were greatest for hard onsets and least for breathy onsets. The results suggest that one trajectory seems to be used with increases in gesture duration being accompanied by decreases in articulator stiffness when moving from hard to normal to breathy voice onset types.     

Extrusion of pastes with a piston extruder for the determination of the local solid and fluid concentration, the local porosity and saturation and displacement profiles by means of NMR imaging

 Nuclear Magnetic Resonance (NMR) was used to investigate the extrusion behaviour of PTFE pastes in a ram extruder. By means of ¹H-NMR imaging (MRI) it is possible to determine the local proton density and therefore, the local fluid concentration. The ¹⁹F-MRI provides the local solid concentration. Thus the local saturation and the local porosity can be calculated with the information of the local fluid and solid concentration. Furthermore displacement profiles can be derived from NMR images by means of correlation techniques without any preparation or marking of the pastes. Received: 8 May 2000   Accepted: 1 May 2001     

Computer simulation of low-energy displacement events in pure HCP metals

Abstract

Molecular dynamics simulations of low-energy atomic recoils have been carried out for α-Ti (HCP) with a view to investigating the displacement threshold energy, E_d, in detail. These have been undertaken at 0 K and 100 K, using a many-body interatomic potential modified to reflect the dominant two-body interaction at short range. This is the first systematic study of atomic displacement events in the HCP structure using such a potential. The mechanisms of these threshold events have been investigated and the strong orientation dependence of the threshold energy has been interpreted in terms of the HCP crystal structure. Also, a correlation has been found between the magnitude of the threshold displacement energy and the maximum number of atoms temporarily displaced into interstitial positions during a cascade.     

ITER超导纵场线圈内馈线系统传热分析

ITER超导纵场线圈内馈线系统位于主机杜瓦内,由18个盒体分别悬挂于相应纵场磁体终端,通过连接件组成多边形环。通过对内馈线在整个装置降温收缩过程的分析,采用有限元分析法对内馈线稳态及瞬态温度场进行数值模拟,得到内馈线的热负荷值、温度分布、温度及变形的时间历程曲线,为内馈线冷却方案的确定和降温时间的预测等提供了可靠验证。     

马氏定律与哈勃定律的辨析

本文从理论,实验上论证了“马氏（红移）定律”,同时指出所谓“退行速度Vr”或“星系红移”与“星系间的距离”无必须的关系,从这个意义上来说,哈勃定律是错误的。     

基于应变片的自由活塞斯特林制冷机位移测试研究

压缩活塞与排出器的位移大小及相位差对自由活塞斯特林制冷机的制冷性能具有极其重要的影响。文中通过对目前各种位移测试方法优缺点分析,结合自由活塞式斯特林制冷机自身特点,提出了采用应变片响应涡旋柔性弹簧形变来测量活塞和排出器位移的新方法。通过分析、设计和标定,建立了一套基于应变片的自由活塞斯特林制冷机位移测量系统。实验测试结果表明,该位移测量系统是可靠的,具有体积小、投资省等优点,且不需要特别的安装空间。     

喷流耦合式超声位移传感器的设计

本文主要研究一种新型微位移传感器。它用超声波原理进行检测，以喷流的水柱作为超声波传播的介质，可以在恶劣环境下进行位移测量。位移等于超声波传播的速度与超声波从发到收之间传播时间的乘积。考虑到声速会随介质一水的温度的升高而增大，设计时进行了实时温度补偿，提高了系统的精度。