Research on Instantaneous Angular Speed Signal Separation Method for Planetary Gear Fault Diagnosis

Planetary gear train is a critical transmission component in large equipment such as helicopters and wind turbines. Conducting damage perception of planetary gear trains is of great significance for the safe operation of equipment. Existing methods for damage perception of planetary gear trains mainly rely on linear vibration analysis. However, these methods based on linear vibration signal analysis face challenges such as rich vibration sources, complex signal coupling and modulation mechanisms, significant influence of transmission paths, and difficulties in separating damage information. This paper proposes a method for separating instantaneous angular speed (IAS) signals for planetary gear fault diagnosis. Firstly, this method obtains encoder pulse signals through a built-in encoder. Based on this, it calculates the IAS signals using the Hilbert transform, and obtains the time-domain synchronous average signal of the IAS of the planetary gear through time-domain synchronous averaging technology, thus realizing the fault diagnosis of the planetary gear train. Experimental results validate the effectiveness of the calculated IAS signals, demonstrating that the time-domain synchronous averaging technology can highlight impact characteristics, effectively separate and extract fault impacts, greatly reduce the testing cost of experiments, and provide an effective tool for the fault diagnosis of planetary gear trains.

Effects of Light Stress on Oxygen Evolution and Photochemical Energy Stor age of Hybrid Poplar Clones Determined by Photoacoustic Technique

The oxygen evolution, thermal dissipation, and photochemical energy storage of three hybrid poplar clones, namely the triploid clone B342, the diploid clone B11 [(Populus alba×P. glandulosa)×(P.tomentosa×P.bolleana)], and the triploid clone B346 [(P.tomentosa×P. bolleana)×(P. alba×P.glandulosa)], under light stress were studied using photoacoustics. The oxygen evolution signal and photochemical energy storage varied negatively with the pretreatment_PFD (photon flux density), whereas the thermal signal varied positively with the pretreatment_PFD. Photochemical energy storage was reallocated to PSⅡ more than to PSⅠ, while the photochemical energy storage in PSⅠ was more stable than that in PSⅡ when subjected to light stress. The inhibitors streptomycin (SM), dithiothreitol (DTT) and sodium fluoride (NaF) could all affect the oxygen evolution signal. Clones B11 and B342 were more resistant to light stress than clone B346.

Gastroscopy-conjugated photoacoustic and ultrasonic dual-mode imaging for detection of submucosal gastric cancer:in vitro study

This paper presents photoacoustic and ultrasonic dual-mode imaging for real-time detection of submucosal gastric cancer with a combination of gastroscopy.The diagnostic capacity was directly addressed via several phantoms and ex vivo experiments.Results demonstrated that superficial and submucosal gastric cancer can be diagnosed with a perceptible depth of 6.33 mm,a lateral accuracy of 2.23 mm,and a longitudinal accuracy of 0.17 mm though capturing the morphology of angiogenesis,which is a main character of the therioma-related change.The capability of gastroscopy-conjugated photoacoustic and ultrasonic dual-mode imaging system will own great potential in improving the clinical diagnostic rate of submucosal gastric cancer.

Development of a Compact Photoacoustic Tomography Imaging System with Dual Single-Element Transducers for Image Enhancement

Objective:This paper proposes a new photoacoustic computed tomography(PACT)imaging system employing dual ultrasonic transducers with different frequencies.When imaging complex biological tissues,photoacoustic(PA)signals with multiple frequencies are produced simultaneously;however,due to the limited bandwidth of a single-frequency transducer,the received PA signals with specific frequencies may be missing,leading to a low imaging quality.Methods:In contrast to our previous work,the proposed system has a compact volume as well as specific selection of the detection center frequency of the transducer,which can provide a comprehensive range for the detection of PA signals.In this study,a series of numerical simulation and phantom experiments were performed to validate the efficacy of the developed PACT system.Results:The images generated by our system combined the advantages of both high resolution and ideal brightness/contrast.Conclusion:The interchangeability of transducers with different frequencies provides potential for clinical deployment under the circumstance where a single frequency transducer cannot perform well.

Simulation Platform of Multi-Pulse Photoacoustic Microscopy Based on K-Space Pseudospectral Method

Photoacoustic imaging has emerged in the past decades. Compared with the traditional medical imaging mode, it has better imaging performance and has great development potential in the field of biological imaging. In traditional photoacoustic microscopy, a single laser pulse is generally used to irradiate the sample to produce photoacoustic signal. And sig-nal-to-noise ratio (SNR) is a very important indicator for photoacoustic im-aging. In order to obtain the image with high SNR, multiple acquisition or increasing laser pulse energy is usually adopted. The former will lead to slower imaging speed, and the latter will lead to photobleaching or pho-totoxicity. Here, we propose multi-pulse photoacoustic microscopy, the photoacoustic signals were stimulated sequentially using multiple laser pulses in each A line data acquisition. In order to verify the feasibility of this method, a multi-pulse photoacoustic imaging simulation platform is established using k-Wave toolbox. The performance of multi-pulse photo-acoustic imaging is verified through the three scanning modes of photoa-coustic microscopy A-scan, B-scan, and C-scan. The results indicate that the SNR is proportion to the number of laser pulses used, high SNR can be achieved by low-energy laser pulse. This work will help to expand the ap-plication of photoacoustic imaging.

Integrated system of traditional THz time-domain spectroscopy and asynchronous optical sampling

Terahertz time-domain spectroscopy(THz-TDS)system,as a new means of spectral analysis and detection,plays an increasingly pivotal role in basic scientific research.However,owing to the long scanning time of the traditional THz-TDS system and the complex control of the asynchronous optical scanning(ASOPS)system,which requires frequent calibration,we combine traditional THz-TDS and ASOPS systems to form a composite system and propose an all-fiber trigger signal generation method based on the time overlapping interference signal generated by the collinear motion of two laser pulses.Finally,the time-domain and frequency-domain spectra are obtained by using two independent systems in the integrated systems.It is found that the full width at half maximum(FWHM)of the time-domain spectra and the spectral width of the frequency-domain spectra are almost the same,but the sampling speed of the ASOPS system is significantly faster than that of the traditional THz-TDS system,which conduces to the study of the transient characteristics of substances.

基于超材料结构的宽频带高频光声信号定向传输模型设计

为了解决高频光声信号在传输过程中存在损耗严重等问题对光声成像技术应用的限制,在声学超材料结构上设计了一种用于实现宽频带高频光声信号定向传输的模型,通过COMSOL Multiphysics软件进行了模型建立,并进行了仿真测试。测试结果表明模型对200~1000 kHz的高频声波均有良好的定向传输效果,具备良好的宽频带定向低损耗传输特性,可以很好地解决高频声波传输过程中容易产生的声能损耗问题。以700 kHz的光声信号为例,研究了光声信号在模型中的传输特性。研究表明该模型在传输高频声波的过程中,能够达到很好的局域声场增强的效果,该模型可以满足光声成像技术在应用过程中的高频信号传输的需求。

基于声波干涉的异常形态红细胞检测技术研究

为了能够在细胞光声波相互干涉的条件下,检测出两个红细胞中是否存在形态异常的细胞,对双细胞光声光谱影响参数进行了有限元分析。建立了单细胞模型、不同距离下的双细胞模型以及相同距离下存在异常形态细胞的双细胞模型,并进行了声场分析。利用单个细胞确定细胞信号的主要分布频率,不同距离下的细胞模型确定合适距离以及探测点的位置分布,相同距离下存在异常形态细胞的双细胞模型确定异常状态下的信号曲线。结果表明,当双细胞均为正常红细胞时,该模型的频域声压级曲线与单细胞信号对比后的弗雷歇距离小于3.3;当双细胞中存在异常形态红细胞时,该模型的频域声压级曲线与单细胞信号对比后的弗雷歇距离大于13.7。因此,在双细胞光声波相互干涉的条件下,将探测点布置在加强区,通过与单个细胞信号对比可以判定两个红细胞中是否存在异常形态的红细胞。

光声光谱气体检测系统中光声池的仿真优化设计

针对特定场合对光声光谱气体检测系统中光声池特征频率的设计需求,利用有限元分析法,以一阶圆柱形共振光声池为研究对象进行声学模态仿真,获得了前8阶声学模态;仿真分析谐振腔、缓冲室的半径和长度对光声池特征频率和光声信号强度的影响。仿真结果表明:当谐振腔半径为3 mm时,谐振腔长度为120 mm,缓冲室的半径、长度分别为14.7 mm、60 mm是光声池特征频率在1400 Hz附近的最佳尺寸。

Comparison of the effects of water temperature on the photoacoustic signals

Acoustic impulses produced through the mechanism of the laser-induced breakdown in water have been investigated in the range from 0℃ to room temperature. Differently from the acoustic impulses produced via thermal expansion, the polarity and the amplitude of acoustic impulse produced via liquid breakdown mechanism do not change with water temperature. This indirectly proves that the production of acoustic impulse is due to the expansion of the cavity itself which includes plasma. A semiempirical description of this phenomenon is given in this paper.

基于不同频率成份衰减矫正的光声成像方法

根据超声衰减理论,研究了光声信号不同频率成份随距离的衰减差异,及其对光声图像重建的影响;提出了对光声信号不同频率成份进行衰减矫正的成像方法,此方法增强了光声信号的高频成份,突出了吸收体的边界变化和细微的结构特征,提高了成像系统分辨率,实验结果显示系统分辨率由0.3mm提高到0.2mm.实验所用的光源为YAG激光器,波长为1064nm,重复频率为20Hz,脉宽为6ns,探测器为针状的PVDF膜水听器,接收面积的直径为1mm.

基于互相关与混沌检测相结合的光声信号检测方法

采用光声光谱方法检测变压器油中溶解气体的体积分数时,由于变压器运行现场的干扰以及检测过程中存在的噪声使得微弱光声信号湮没在强噪声中而无法辨识。在分别对互相关运算和混沌检测进行分析说明的基础上将这2种方法结合起来作为微弱光声信号检测的理论依据。集成LabVIEW和Matlab软件构建了虚拟信号检测系统,编程实现了由李雅普诺夫特性指数谱来判定混沌系统运动状态的功能。实验结果表明该方法对被强噪声覆盖的微弱光声信号非常敏感,具有较高检测精度。

光声成像技术在生物医学中的研究进展

简要介绍了生物医学中的光声成像技术机理,总结报道了国内外几种典型的光声成像方法和光声图像重建算法的发展历程及其最新进展,指出该技术是一种很有应用前景的医学检测方法。

基于CEEMDAN的光声光谱CO检测技术

为实现高灵敏度痕量CO气体探测,设计并实现了一种基于光声光谱的CO气体传感器,采用近红外分布反馈式激光器和掺铒光纤放大器作为激励光源系统,结合双通道差分光声池降低系统噪声。用自适应噪声的完备经验模态分解算法结合Savitxky-Golay滤波器对采集的非线性光声信号进行降噪,通过评估降噪后分量与原始信号的相关系数选取有效模态并重构。实验结果表明,室温和常压条件下,积分时间为100 ms,经算法处理,该系统CO检测信噪比提高至原来的4.6倍,最低检测极限降低到2.6×10^(-6),且该传感器对气体浓度具有良好的线性响应,验证了该算法在提高光声光谱系统检测性能方面的可行性与有效性。

光声信号强度与溶液浓度关系的研究

研究了光声信号的强度与溶液浓度的关系．应用光谱学比尔定律和液体光声理论，得出了在溶液浓度不太大的条件下，光声信号强度与溶液浓度成线性关系的结论．实验结果与理论计算吻合．

基于虚拟仪器的光声信号采集和成像系统

为了实现光声信号的快速采集和图像重建,采用基于虚拟仪器的光声信号采集和成像系统进行光声信号采集,由LABVIEW调用MATLAB程序对采集到的数据进行处理,最后利用滤波反投影重建算法,实现了对模拟组织样品的光声层析成像。成像系统的分辨率为0.15mm,重建图像与实物十分吻合。结果表明,该系统具有快速、方便、直观等特点,有望发展成为一种低成本的实用的临床诊断仪器。

变压器油中溶解气体光声信号检测的干扰抑制方法

光声光谱气体检测技术能很好地应用于变压器油中溶解气体的在线监测,为了提高其检测信噪比,笔者针对光声信号检测的强噪声环境,结合小波阈值去噪和混沌检测来抑制检测过程中的强噪声干扰,配合使用LabVIEW和Simulink构建信号检测系统提取微弱光声信号。实验结果表明该方法对被强噪声覆盖的微弱周期信号非常敏感,能有效地抑制强噪声干扰。

煤矿瓦斯气体的光声光谱检测研究

煤矿瓦斯(CH4)是一种可用于诊断煤矿安全生产的特征气体。光声光谱技术是一种新型的气体检测技术,具有选择性好、灵敏度高、动态监测范围大、不消耗被测气体等优点,能很好地应用到CH4气体的在线监测。基于光声光谱技术的基本原理,利用分布反馈半导体激光器构建一种用以检测CH4的光声光谱装置,利用该装置研究了气体光声信号与CH4浓度、温度、斩波频率、激光功率、背景气体、以及压强之间的关系,并测得甲烷在2ν3带的R(3)支的光声光谱。

高强度激光斜入射时涂漆光声信号变化趋势

高强度激光斜入射时涂漆光声信号变化趋势王阳恩尚志远董彦武王公正李争光（陕西师范大学应用声学研究所，西安７１００６２；第一作者，男，２８岁，硕士）自从１９７３年Ｒｏｓｅｎｃｗａｉｇ提出固体光声谱技术并创立ＲＧ固体光声理论以来，有关光声技术与理论的研究得...

激光偏振方向对光声信号的影响

在高强度激光照射下材料表面会产生蒸发，形成等离子体。如果激光是斜入射材料表面的，则材料光声信号的大小与激光的偏振方向有关。本文通过实验研究了在相同的激光入射角的情况下，光声信号的大小随激光偏振方向的变化关系，得出了激光偏振方向与激光入射面的夹角为０ 度时，光声信号最强；而其夹角为９０ 度时，光声信号为极小值。