航空原位涡流无损检测传感器数控阻抗信号调理电桥研究

针对航空航天装备现场原位涡流无损检测(ECNDT)快速化、智能化、集成化的需求,提出了一种应用于原位涡流无损检测系统的新型数控传感器阻抗信号调理电桥,从设计思路、理论分析、电桥结构、工程实现方法以及性能分析等方面对其进行了详尽的阐述,最后通过具体的航空装备现场原位实验(某型飞机发动机九级蓖齿盘)验证了该数控阻抗信号调理电桥方法的有效性。

一种有效降低测量噪声的新方法

利用信号与测量噪声在小波分析中不同尺度上的传播特性,研究了小波技术在涡流无损检测信号除噪中的应用。分析了传统的去除测量噪声的两种小波方法,Mallat多尺度边缘检测方法和阈值方法,针对两种方法的不足,提出了一种新方法:低分辨率下的小波分解系数全部保留,高分辨率下的小波系数则只有被确认为有用信号特征值及其附近各点才予以保留,其余的都加以去除。结果表明,此方法能有效地降低测量噪声。

Generalization of the Second Order Vector Potential Formulation for Arbitrary Non-Orthogonal Curvilinear Coordinates Systems from the Covariant Form of Maxwell's Equations

A great number of semi-analytical models, notably the representation of electromagnetic fields by integral equations are based on the second order vector potential (SOVP) formalism which introduces two scalar potentials in order to obtain analytical expressions of the electromagnetic fields from the two potentials. However, the scalar decomposition is often known for canonical coordinate systems. This paper aims in introducing a specific SOVP formulation dedicated to arbitrary non-orthogonal curvilinear coordinates systems. The electromagnetic field representation which is derived in this paper constitutes the key stone for the development of semi-analytical models for solving some eddy currents moelling problems and electromagnetic radiation problems considering at least two homogeneous media separated by a rough interface. This SOVP formulation is derived from the tensor formalism and Maxwell’s equations written in a non-orthogonal coordinates system adapted to a surface characterized by a 2D arbitrary aperiodic profile.