基于谱线特征的羊绒与羊毛的鉴别

为快速区分和检验羊毛、羊绒,提出基于羊毛与羊绒谱线特征的识别方法。这种方法先通过光学显微镜获得羊毛与羊绒的图像,然后经过图像处理得到羊毛与羊绒的表面信息。接着通过投影的方式,获得羊毛与羊绒表面所对应的谱线。对获得的谱线进行分割,根据羊毛及羊绒谱线的特性不同,提取羊毛及羊绒谱线的单元宽度值、单元峰值及离散系数、峰值宽度比等参数;最后通过对这些参数的分析处理进行识别。实验结果表明,采用这种方法识别羊毛及羊绒,不仅快速准确,而且与以往的方法相比,在精度和速度上都有显著的提高。     

Effects of the number of inducer blades on the anti-cavitation characteristics and external performance of a centrifugal pump

Installing an inducer upstream of the main impeller is an effective approach for improving the anti-cavitation performance of a highspeed centrifugal pump. For a high-speed centrifugal pump with an inducer, the number of inducer blades can affect its internal flow and external performance. We studied the manner in which the number of inducer blades can affect the anti-cavitation characteristics and external performance of a centrifugal pump. We first use the Rayleigh-Plesset equation and the mixture model to simulate the vaporliquid flow in a centrifugal pump with an inducer, and then predict its external performance. Finally, we tested the external performance of a centrifugal pump with 2-, 3-and 4-bladed inducers, respectively. The results show that the simulations of external performance in a centrifugal pump are in accordance with our experiments. Based on this, we obtained vapor volume fraction distributions for the inducer, the impeller, and in the corresponding whole flow parts. We discovered that the vapor volume fraction of a centrifugal pump with a 3-bladed inducer is less than that of a centrifugal pump with 2-or 4-bladed inducers, which means that a centrifugal pump with a 3-bladed inducer has a better external and anti-cavitation performance.

     

利用LabVIEW设计Palm与单片机间多通道串口通信的方法

针对目前串口通信的研究大都只停留在PC机与单片机之间,或只用文本语言开发PDA与单片机的串口通信这一现状,研制了一套以PIC16F873为下位机,Palm OS为上位机操作平台,LabVIEW7．0为开发语言的串口通信系统。给出了该系统的硬件、软件设计方案及模拟测试结果。实验证明其工作性能稳定、界面友好、用户操作方便。