小波变换在差动热分析仪信号处理中的应用

Application research of wavelet transform in signal process of differential scanning calorimetry(DSC)

差动热分析仪广泛应用于测定物质在程序温度控制下产生物理或化学性质变化时所发生的热效应与相应温度。为提高差动热分析仪的分析精度,应用虚拟仪器技术对差动热分析仪的数据采集、数据分析系统进行了开发,介绍了在LabVIEW环境下,结合MATLAB小波工具箱提供的小波分析功能函数,对采集的差热信号进行去噪预处理的方法,着重对小波基函数的选择以及阈值的选择问题进行了详细的讨论。比较了5种可用于噪声处理的小波函数对热分析信号DSC曲线预处理的结果。结果表明,对于类似正弦的比较平滑的DSC信号,采用sym8小波rigrsure准则去噪可以达到很好的滤波效果。

DSC is widely used in measuring the material＇s when the material＇ s physical or chemical character changes heat effect and corresponding temperature under the procedure temperature control. To improve the DSC＇s analytical precision, the DSC ＇ s data acquisition and data analysis system are researched by using the virtual instrument technique. The DSC signals were de-noising pretreated under the enviroment of LabVIEW based on wavelet analysis functions provided by MATLAB wavelet toolbox. The problems of wavelet basic function＇ s selection and threshold＇ s selection are discussed then. Five wavelet functions which can be used in de-noising pretreatment to the DSC curves are compared. As a result, for the similar sinusoidal smoothed curves, a good filtering result can be obtained by using the sym8 wavelet and rigrsure rule.