基于红外波段光谱吸收的小型化湿度探测系统

 探测系统的光源选择为垂直腔面发射激光器,选定水汽在1.854 μm的吸收峰。系统自动在直接测量法与谐波测量法之间切换,能够适应高低湿度环境。在低湿度环境检测中,利用二次谐波与一次谐波的比值来定标湿度,有效去除了光源不稳定对测量带来的影响;过采样的A/D转换结合数字锁相放大（DLIA）技术,提高了检测精度。系统通过以太网接口,可以实现远程数据采集。     

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为适应我国信息化建设需要,实现科技期刊编辑、出版、发行工作的电子化,推进科技信息交流网络化的进程,扩大作者学术交流渠道,本刊已加入《中国学术期刊(光盘版)》和"中国期刊网"。并入网"万方数据——数字化期刊群"和"书生数字期刊"。作者著作权使用费与本刊稿酬一次性给付。如作者不同意将文章编入该数据库,请     

基于声表面波技术实现数字微流体多基片间输运

建立了声表面波实现多基片间输运微流体的新方法.由3个128(0)YX-LiNbO3压电基片组成,一个基片为接口基片,另两个为工作基片,每个基片光刻一个中心频率为27.5 MHz叉指换能器和一个反射栅.采用微量进样器将待输运的数字微流体进样到工作基片2,调节接口基片使得其与工作基片2位于同一高度,并使其间隙尽可能小,在工...     

A STUDY ON THE COUNTER-INTUITIVE BEHAVIORS OF PIN-ENDED BEAMS UNDER PROJECTILE IMPACT

The counter-intuitive behaviors of pin-ended beams under the projectile impact are investigated with ANSYS/LS-DYNA in this paper. It studies in detail their displacement-time history curves, final deformed shapes, energy relationships and projectile impact velocity ranges related to their counter-intuitive behaviors. The influences of the impact positions on their counterintuitive behaviors are also discussed. The results show that no matter where the impact position on the beam is, the counter-intuitive behaviors of pinned beams will occur as long as the impacting velocity lies within a proper range. Corresponding to the occurring of the counter-intuitive behaviors, the rebounding number in the displacement history curves of the beams decreases from a few times to zero with an increase of the impact velocity. The final deformation modes of the beam corresponding to the counter-intuitive behaviors will appear in symmetrical and unsym-metrical forms no matter where the impact position is; the impact velocity of the first-occurring of the counter-intuitive behaviors of the beam increases slowly with the deviation of the impact position away from the mid-span.     

用于显微图像和平滑图像的梯度数字相关法

随着微观实验力学技术的发展,显微图像的相关分析与计算变得越来越重要.与以往的宏观图像和散斑图像相比,显微图像具有明显不同的特点,即团状,灰度变化平缓、大颗粒等.为了对这类图像进行稳定、较高精度的分析,本文提出了微区图像梯度数字相关方法,并通过实验探讨了所提算法的检测性能.     

宝泉抽水蓄能电站岩体抗剪参数的选取

本文讨论了岩体抗剪参数C、f值的选取方法, 推导了C、f值的数字特征公式。通过对宝泉抽水蓄能电站工程岩体抗剪参数的选取, 结果表明：由于岩体抗剪参数具有随机性和模糊性, 采用随机-模糊法选取的C、f值要符合实际；文中给出的数字特征公式可对C、f值的波动性及相关性进行检验。     

散斑与数字技术

本文总结了过去十年中散斑数字技术在力学、医学、无线电电子学和天文学中的应用和进展,以及在这些领域中所发展的各种新的理论、实验技术和实验方法。     

相关识别中的曲面拟合法

本文讨论了相关识别中的曲面拟合法。利用相关系数在真实匹配点附近的统计特性,通过对相关系数进行曲线（一维）或曲面（二维）拟合,根据其一阶导数确定最大相关系数所在的位置,快速得到亚像素匹配点。与逐步搜索法相比,该方法大大减少了运算次数,提高了数字图像相关运算的速度。     

Numerical simulation of unsteady interaction of centrifugal impeller with its diffuser using Lagrangian discrete vortex method

In this study, an advanced Lagrangian vortex- boundary element method is applied to simulate the unsteady impeller-diffuser interactions in a diffuser pump not only for design but also for off-design considerations. In velocity calculations based on the Biot-Savart law we do not have to grid large portions of the flow field and the calculation points are concentrated in the regions where vorticity is present. Lagrangian representation of the evolving vorticity field is well suited to moving boundaries. An integral pressure equation shows that the pressure distribution can be estimated directly from the instantaneous velocity and vorticity field. The numerical results are compared with the experimental data and the comparisons show that the method used in this study can provide us insight into the complicated unsteady impeller-diffuser interaction phenomena in a diffuser pump.     

蒙特卡罗方法初步—椭圆内均匀分布的抽样技巧

以简明通俗的语言，避开统计学中抽象的数学公式和符号，介绍了作为计算数学一个独立分支的蒙特卡罗方法的基本思想和概念、蒙特卡罗方法在粒子输运问题中的应用以及最基本的几种抽样方法，最后介绍一种椭圆内均匀分布的蒙特卡罗“压缩”抽样方法及其证明。