查看更多>>摘要：A prism-excited multilayer film Surface Plasmon Resonance (SPR) sensing structure of graphene-silver-graphenemeasured mediums is proposed to solve the unstablility and oxidization problem of metallic silver films for SPR sensors.By adding a graphene layer,the poor stability and the oxidization problem of silver film are solved.The electromagnetic field and reflection mechanism of the multilayer film structure are theoretically analyzed.The characteristics of the different metal materials for SPR,the distinct silver film thickness,and different graphene layers are studied through experiments to optimize the sensor design.Compared with the gold film sensor,the sensitivity of the multilayer film sensor with graphene layer is improved.The designed SPR sensor is used to detect a sucrose solution with a concentration of 0％-64％,and its refractive index is 1.33 to 1.45,linear correlation coefficient is 0.998 4.Good resonance effect and sensing characteristics are thus obtained.
查看更多>>摘要：The converter is the core component of voltage source converter-high voltage direct current (VSC-HVDC),which is related to the stable operation of the system.The converter has a complex structure where the accuracy of feature extraction is low,and the computation speed of traditional fault diagnosis strategies is slow.To solve this problem,a fault diagnosis strategy based on wavelet singular entropy (WSE) and support vector machine (SVM) was proposed.This method includes fault and label setting,converter fault feature extraction based on wavelet singular entropy,and converter fault classification based on support vector machine.The DC-side voltage signal was used as the detection signal,and the wavelet singular entropy was used for feature extraction to avoid noise interference.The classification is based on SVM.The experimental verification in PSCAD simulation proved that the method has better fault diagnosis ability for various faults and meets the needs of converter fault diagnosis.
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