Parametric signal representation techniques with Chirplet models have attracted much attention in ultrasonic guided waves-based research of material property identification and structural integrity evaluation. The known Chirplet models are established using either the Gaussian windows or the linear chirp function. This is inconsistent with practical situations where the excitation is a Hanning-windowed sinusoidal signal, and the received signals have a nonlinear phase and asymmetric envelope due to the dispersive nature of the waves. A nonlinear Hanning-windowed Chirplet (NHWC) model was proposed to eliminate the above inconsistencies in which a nonlinear phase modulation term was designed to modulate the classical Hanning-window and the sine function. The phase modulation term was established with the hyperbolic tangent function. The mathematical properties of the nonlinear phase modulation term and the NHWC model were analyzed mathematically, including the time variability, parity, concavity, and convexity of the phase. These were used to guide the parameter setting in parametric signal representation techniques. The NHWC model can characterize various characteristics of guided waves signals, including the symmetric or asymmetric Hanning envelopes and the phase nonlinearity. Finally, an adaptive genetic algorithm was adopted to verify the effectiveness of the NHWC model in the parameter representation of experimentally measured ultrasonic signals.

中文翻译：

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用于超声导波信号参数表示的非线性汉宁窗口 Chirplet 模型

Chirplet 模型参数化信号表示技术在基于超声导波的材料特性识别和结构完整性评估研究中备受关注。已知的 Chirplet 模型是使用高斯窗口或线性 chirp 函数建立的。这与激励是汉宁窗正弦信号的实际情况不一致，并且由于波的色散性质，接收信号具有非线性相位和不对称包络。提出了一种非线性汉宁窗 Chirplet (NHWC) 模型来消除上述不一致，其中设计了非线性相位调制项来调制经典汉宁窗和正弦函数。相位调制项是用双曲正切函数建立的。对非线性相位调制项和NHWC模型的数学性质进行了数学分析，包括相位的时变性、奇偶性、凹度和凸度。这些用于指导参数信号表示技术中的参数设置。NHWC 模型可以表征导波信号的各种特性，包括对称或非对称汉宁包络和相位非线性。最后，采用自适应遗传算法验证了NHWC模型在实验测量超声信号参数表示中的有效性。这些用于指导参数信号表示技术中的参数设置。NHWC 模型可以表征导波信号的各种特性，包括对称或非对称汉宁包络和相位非线性。最后，采用自适应遗传算法验证了NHWC模型在实验测量超声信号参数表示中的有效性。这些用于指导参数信号表示技术中的参数设置。NHWC 模型可以表征导波信号的各种特性，包括对称或非对称汉宁包络和相位非线性。最后，采用自适应遗传算法验证了NHWC模型在实验测量超声信号参数表示中的有效性。