An optical fiber hydrophone based on equivalent phase shift fiber Bragg grating （EPS-FBG） with temperature compensation package provides an improvement of sensitivity in underwater acoustic measurement at wide frequ...An optical fiber hydrophone based on equivalent phase shift fiber Bragg grating （EPS-FBG） with temperature compensation package provides an improvement of sensitivity in underwater acoustic measurement at wide frequency range, from 2.SkHz to 12kHz. The acoustic pressure is transduced into elastic vibration of a circle metal disk, resulting in an intensity modulation of the reflected light wave back from fiber Bragg grating （FBG）. Experiment shows that the 500 EPS-FBG hydrophone has a minimum detectable acoustic pressure of about at 5 kHz and achieves about 18-dB improvement of acoustic pressure sensitivity compared with a regular apodized FBG hydrophone.展开更多
为了降低拖拉机驾驶室内中高频噪声,建立基于统计能量分析(SEA)方法的驾驶室内噪声预测模型。通过理论计算和试验方法确定模型的基本参数和激励输入,通过仿真与试验对比验证了SEA模型的准确性。最后对驾驶室内声腔的功率输入分析,得到...为了降低拖拉机驾驶室内中高频噪声,建立基于统计能量分析(SEA)方法的驾驶室内噪声预测模型。通过理论计算和试验方法确定模型的基本参数和激励输入,通过仿真与试验对比验证了SEA模型的准确性。最后对驾驶室内声腔的功率输入分析,得到对驾驶室内噪声贡献较大的板件子系统,据此提出有针对性的声学包装改进方案,仿真结果表明该声学包装设计方案可以有效降低驾驶室内中高频噪声,总声压级降低1.87 d B(A),为拖拉机驾驶室内噪声控制及声学包装优化提供有效依据。展开更多
Vehicle interior noise has emerged as a crucial assessment criterion for automotive NVH(Noise,Vibration,and Harshness).When analyzing the NVH performance of the vehicle body,the traditional SEA(Statistical Energy Anal...Vehicle interior noise has emerged as a crucial assessment criterion for automotive NVH(Noise,Vibration,and Harshness).When analyzing the NVH performance of the vehicle body,the traditional SEA(Statistical Energy Analysis)simulation technology is usually limited by the accuracy of the material parameters obtained during the acoustic package modeling and the limitations of the application conditions.In order to effectively solve these shortcomings,based on the analysis of the vehicle noise transmission path,a multi-level objective decomposition architecture of the interior noise at the driver’s right ear is established.Combined with the data-driven method,the ResNet neural network model is introduced.The stacked residual blocks avoid the problem of gradient dis-appearance caused by the increasing network level of the traditional CNN network,thus establishing a higher-precision prediction model.This method alleviates the inherent limitations of traditional SEA simulation design,and enhances the prediction performance of the ResNet model by dynamically adjusting the learning rate.Finally,the proposed method is applied to a specific vehicle model and verified.The results show that the proposed meth-od has significant advantages in prediction accuracy and robustness.展开更多
C-mode scanning acoustical microscopy, C-SAM, is widely used in plastic package evaluations and for failure analysis. It permits to detect subsurface delaminations, cracks and pores （air bubbles） for different micro...C-mode scanning acoustical microscopy, C-SAM, is widely used in plastic package evaluations and for failure analysis. It permits to detect subsurface delaminations, cracks and pores （air bubbles） for different microelectronics packages. In this study, abnormality was observed in C-SAM daily test, the images showed no delaminations but inhomogeneities on the IC surface. Corrosion was found by optical microscope and scanning electron microscope after decapsulation. It can be revealed as the acoustic impedance is different between corrosion and normal area. The presence of inhomogeneities and discontinuities along ultrasonic waves＇ propagation paths inside the matter causes modifications in the amplitude and polarity of ultrasonic waves. However, C-SAM＇s capability in detecting IC surface corrosion has not been presented. The capability will be illustrated and the inspection mechanism will be discussed in this paper.展开更多
文摘An optical fiber hydrophone based on equivalent phase shift fiber Bragg grating （EPS-FBG） with temperature compensation package provides an improvement of sensitivity in underwater acoustic measurement at wide frequency range, from 2.SkHz to 12kHz. The acoustic pressure is transduced into elastic vibration of a circle metal disk, resulting in an intensity modulation of the reflected light wave back from fiber Bragg grating （FBG）. Experiment shows that the 500 EPS-FBG hydrophone has a minimum detectable acoustic pressure of about at 5 kHz and achieves about 18-dB improvement of acoustic pressure sensitivity compared with a regular apodized FBG hydrophone.
文摘为了降低拖拉机驾驶室内中高频噪声,建立基于统计能量分析(SEA)方法的驾驶室内噪声预测模型。通过理论计算和试验方法确定模型的基本参数和激励输入,通过仿真与试验对比验证了SEA模型的准确性。最后对驾驶室内声腔的功率输入分析,得到对驾驶室内噪声贡献较大的板件子系统,据此提出有针对性的声学包装改进方案,仿真结果表明该声学包装设计方案可以有效降低驾驶室内中高频噪声,总声压级降低1.87 d B(A),为拖拉机驾驶室内噪声控制及声学包装优化提供有效依据。
基金This research was funded by the SWJTU Science and Technology Innovation Project,Grant Number 2682022CX008the Natural Science Foundation of Sichuan Province,Grant Numbers 2022NSFSC1892,2023NSFSC0395.
文摘Vehicle interior noise has emerged as a crucial assessment criterion for automotive NVH(Noise,Vibration,and Harshness).When analyzing the NVH performance of the vehicle body,the traditional SEA(Statistical Energy Analysis)simulation technology is usually limited by the accuracy of the material parameters obtained during the acoustic package modeling and the limitations of the application conditions.In order to effectively solve these shortcomings,based on the analysis of the vehicle noise transmission path,a multi-level objective decomposition architecture of the interior noise at the driver’s right ear is established.Combined with the data-driven method,the ResNet neural network model is introduced.The stacked residual blocks avoid the problem of gradient dis-appearance caused by the increasing network level of the traditional CNN network,thus establishing a higher-precision prediction model.This method alleviates the inherent limitations of traditional SEA simulation design,and enhances the prediction performance of the ResNet model by dynamically adjusting the learning rate.Finally,the proposed method is applied to a specific vehicle model and verified.The results show that the proposed meth-od has significant advantages in prediction accuracy and robustness.
文摘C-mode scanning acoustical microscopy, C-SAM, is widely used in plastic package evaluations and for failure analysis. It permits to detect subsurface delaminations, cracks and pores （air bubbles） for different microelectronics packages. In this study, abnormality was observed in C-SAM daily test, the images showed no delaminations but inhomogeneities on the IC surface. Corrosion was found by optical microscope and scanning electron microscope after decapsulation. It can be revealed as the acoustic impedance is different between corrosion and normal area. The presence of inhomogeneities and discontinuities along ultrasonic waves＇ propagation paths inside the matter causes modifications in the amplitude and polarity of ultrasonic waves. However, C-SAM＇s capability in detecting IC surface corrosion has not been presented. The capability will be illustrated and the inspection mechanism will be discussed in this paper.
