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Capillary effect-based selective sealing strategy for increasing piezoelectric MEMS speaker performance

Microsystems & Nanoengineering 2024年第4期10卷 329-341页

作者： Yan Wang Tunan Lv junning zhang Hongbin Yu School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China Optics Valley Laboratory WuhanHubei 430074China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China

To address the serious acoustic performance deterioration induced by air leakage in the low-frequency range and the asynchronous vibration in electroacoustic transduction structures near the resonant frequency,a novel sealing strategy is proposed that targets one of the most widely reported piezoelectric MEMS speaker *** design consists of multiple cantilever beams,in which the air gaps between cantilevers are automatically and selectively filled with liquid polydimethylsiloxane(PDMS)via the capillary effect,followed by *** the proof-of-concept demonstration,the sound pressure level(SPL)within the frequency range lower than 100 Hz markedly increased after sealing in an experiment using an IEC ear ***,the SPL is increased by 4.9 dB at 20 Hz for a 40 Vpp driving ***,the deteriorated SPL response near the resonant frequencies of the cantilever beams(18 kHz–19 kHz)caused by their asynchronous vibration induced by the fabrication process nonuniformity also significantly improved,which successfully increased the SPL to approximately 17.5 ***,sealed devices feature nearly the same SPL response as the initial counterpart in the frequency band from 100 Hz to 16 kHz and a total harmonic distortion(THD)of 0.728%at 1 kHz for a 40 Vpp driving *** with existing sealing methods,the current approach offers easy operation,low damage risk,excellent repeatability/reliability and excellent robustness advantages and provides a promising technical solution for MEMS acoustic devices.

关键词： sealing piezoelectric effect

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Dirac method for nonlinear and non-homogenous boundary value problems of plates

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 15-38页

作者： Xiaoye MAO Jiabin WU junning zhang Hu DING Liqun CHEN Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Frontier Science Center of MechanoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200444China Shanghai Institute of Aircraft Mechanics and Control Shanghai 200092China

The boundary value problem plays a crucial role in the analytical investigation of continuum dynamics. In this paper, an analytical method based on the Dirac operator to solve the nonlinear and non-homogeneous boundary value problem of rectangular plates is proposed. The key concept behind this method is to transform the nonlinear or non-homogeneous part on the boundary into a lateral force within the governing function by the Dirac operator, which linearizes and homogenizes the original boundary, allowing one to employ the modal superposition method for obtaining solutions to reconstructive governing equations. Once projected into the modal space, the harmonic balance method(HBM) is utilized to solve coupled ordinary differential equations(ODEs)of truncated systems with nonlinearity. To validate the convergence and accuracy of the proposed Dirac method, the results of typical examples, involving nonlinearly restricted boundaries, moment excitation, and displacement excitation, are compared with those of the differential quadrature element method(DQEM). The results demonstrate that when dealing with nonlinear boundaries, the Dirac method exhibits more excellent accuracy and convergence compared with the DQEM. However, when facing displacement excitation, there exist some discrepancies between the proposed approach and simulations;nevertheless, the proposed method still accurately predicts resonant frequencies while being uniquely capable of handling nonuniform displacement excitations. Overall, this methodology offers a convenient way for addressing nonlinear and non-homogenous plate boundaries.

关键词： rectangular plate Dirac operator nonlinear boundary time-dependent boundary boundary value problem

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Influence of vehicle-road coupled vibration on tire adhesion based on nonlinear foundation

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Applied Mathematics and Mechanics(English Edition) 2021年第5期42卷 607-624页

作者： junning zhang Shaopu YANG Shaohua LI Yongjie LU Hu DING School of Traffic and Transportation Shijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang 050043China Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai 200072China

The influence of pavement vibration on tire adhesion is of great significance to the structure design of vehicle and *** adhesion between tire and road is the key to studying vehicle dynamics,and the precise description of tire adhesion affects the accuracy of dynamic vehicle ***,in most models,only road roughness is considered,and the pavement vibration caused by vehicle-road interaction is *** this paper,a vehicle is simplified as a spring-mass-damper oscillator,and the vehicle-pavement system is modeled as a vehicle moving along an Euler-Bernoulli beam with finite length on a nonlinear *** road roughness is considered as a sine wave,and the shear stress is ignored on the *** to the contact form between tire and road,the LuGre tire model is established to calculate the tire adhesion *** Galerkin method is used to simplify the partial differential equations of beam vibration into finite ordinary differential equations.A product-to-sum formula and a Dirac delt function are used to deal with the nonlinear term caused by the nonlinear foundation,which realizes the fast and accurate calculation of super-high dimensional nonlinear ordinary differential *** addition,the dynamic responses between the coupled system and the traditional uncoupled system are compared with each *** obtained results provide an important theoretical basis for research on the influence of vehicle-road coupled vibration on tire adhesion.

关键词： vehicle system dynamics vehicle-road coupled vibration LuGre tire model Galerkin method

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Detection of K in soil using time-resolved laser-induced breakdown spectroscopy based on convolutional neural networks

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Plasma Science and Technology 2019年第3期21卷 108-113页

作者： Chengxu LU Bo WANG Xunpeng JIANG junning zhang Kang NIU Yanwei YUAN Chinese Academy of Agricultural Mechanization Sciences Jiangsu University COFCO Feed Co.Ltd

One of the technical bottlenecks of traditional laser-induced breakdown spectroscopy(LIBS) is the difficulty in quantitative detection caused by the matrix effect. To troubleshoot this problem,this paper investigated a combination of time-resolved LIBS and convolutional neural networks(CNNs) to improve K determination in soil. The time-resolved LIBS contained the information of both wavelength and time dimension. The spectra of wavelength dimension showed the characteristic emission lines of elements, and those of time dimension presented the plasma decay trend. The one-dimensional data of LIBS intensity from the emission line at 766.49 nm were extracted and correlated with the K concentration, showing a poor correlation of R_c^2?=?0.0967, which is caused by the matrix effect of heterogeneous soil. For the wavelength dimension, the two-dimensional data of traditional integrated LIBS were extracted and analyzed by an artificial neural network(ANN), showing R_v^2?=?0.6318 and the root mean square error of validation(RMSEV)?=?0.6234. For the time dimension, the two-dimensional data of time-decay LIBS were extracted and analyzed by ANN, showing R_v^2?=?0.7366 and RMSEV?=?*** higher determination coefficients reveal that both the non-K emission lines of wavelength dimension and the spectral decay of time dimension could assist in quantitative detection of ***, due to limited calibration samples, the two-dimensional models presented *** three-dimensional data of time-resolved LIBS were analyzed by CNNs, which extracted and integrated the information of both the wavelength and time dimension, showing the R_v^2?=?0.9968 and RMSEV?=?0.0785. CNN analysis of time-resolved LIBS is capable of improving the determination of K in soil.

关键词： quantitative detection potassium(K) soil time-resolved laser-induced breakdown spectroscopy(LIBS) convolutional neural networks(CNNs)

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High-speed adaptive photoacoustic microscopy

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Photonics Research 2023年第12期11卷 2084-2092页

作者： LINYANG LI WEI QIN TINGTING LI junning zhang BAOCHEN LI LEI XI Department of Biomedical Engineering Southern University of Science and TechnologyShenzhen 518055China Guangdong Provincial Key Laboratory of Advanced Biomaterials Southern University of Science and TechnologyShenzhen 518055China Shenzhen Bay Laboratory Shenzhen 518132China

Optical-resolution photoacoustic microscopy(OR-PAM)is capable of observing the distribution of optical absorbers inside bio-tissues with a high spatial resolution of ***,due to the employment of a tight optical focus,it suffers from a limited depth of field(DOF),making it challenging to achieve highresolution imaging of targets with arbitrary ***,we propose a high spatiotemporal adaptive photoacoustic focusing mechanism through integrating a high-speed optical focuser,a time-of-flight contour deriving algorithm,and the rotary-scanning photoacoustic *** developed system,named high-speed adaptive photoacoustic microscopy(HA-PAM),features an ultrashort focus-shifting time of 5 ms and an enlarged DOF of up to 5 *** the assistance of the proposed mechanism,we can achieve a homogeneous lateral resolution of 6μm over a 10 mm circular imaging domain within 5 *** demonstrate the advantages of HA-PAM through imaging phantoms with curved surfaces,subcutaneous tumor-bearing mice,resected rabbit kidneys,and pulsating mouse *** imaging results suggest that this approach provides a high and consistent spatial resolution for imaging bio-tissues with arbitrary surfaces without sacrificing the imaging speed,and has the potential to extend the fundamental and clinical applications of OR-PAM.

关键词： resolution absorber shifting

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Weapon Equipment Auxiliary Maintenance Platform based on Augmented Reality Technology

Weapon Equipment Auxiliary Maintenance Platform based on Aug...

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作者： De zhang Guozhang Li Huaiguang Wang junning zhang Department of Vehicle and Electrical Engineering Army Engineering University Shijiazhuang Campus Missile Engineering Department Army Engineering University Shijiazhuang Campus

With the development of science and technology and the progress of society,many largescale equipment with extremely complex structure and high technology density is gradually equipped with our army,and such equipment has very high requirements for the technical level of personnel in the maintenance *** present,the traditional maintenance technology has the problems of poor security and low efficiency,and augmented reality technology,combined with computer vision,machine learning and other fields of knowledge,has become the mainstream method in auxiliary maintenance,which plays an important role in improving *** this paper,Augmented Reality System to Assistance Maintenance Platform（ARSAMP） is ***,the advantages and functions of augmented reality are ***,it gives the development situation of foreign *** the advantages and disadvantages of traditional maintenance and ARSAMP are compared and the advantages and disadvantages of the current maintenance platform are pointed ***,the effective solution to improve the maintenance effect is put forward and the future development direction of the platform is prospected.

关键词： Augmented reality Computer vision Machine learning Auxiliary maintenance

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北京典型耕作土壤养分的近红外光谱分析

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农业工程学报 2012年第2期28卷 176-179页

作者：李颉张小超苑严伟张俊宁土壤植物机器系统技术国家重点实验室中国农业机械化科学研究院北京100083

为研究土壤养分含量分布信息,以从北京郊区一块试验田采集的72个土壤样品为试验材料,应用傅里叶变换近红外光谱技术分析了土样的全氮、全钾、有机质养分含量和pH值。采用偏最小二乘法(PLS)对光谱数据与土壤养分实测值进行回归分析,建立... 详细信息

为研究土壤养分含量分布信息,以从北京郊区一块试验田采集的72个土壤样品为试验材料,应用傅里叶变换近红外光谱技术分析了土样的全氮、全钾、有机质养分含量和pH值。采用偏最小二乘法(PLS)对光谱数据与土壤养分实测值进行回归分析,建立预测模型,以模型决定系数(R2)、校正标准差(RMSECV)、预测标准差(RMSEP)和相对分析误差(RPD)作为模型精度的评价指标。结果表明,利用该模型与光谱数据对土壤全氮、全钾、有机质养分含量和pH值进行预测,结果与实测数据具有较好的一致性,最高决定系数R2达到0.9544。偏最小二乘回归方法建立的养分预测模型能准确地对北京地区褐土土质全氮、有机质、全钾和pH值4种养分进行预测。

关键词：土壤养分傅里叶变换近红外光谱偏最小二乘法

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改进K-SVD算法在曲轴轴承AE信号的去噪研究

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振动与冲击 2017年第21期36卷 150-156页

作者：张峻宁张培林华春蓉秦萍军械工程学院七系石家庄050003 西南交通大学机械工程学院成都610031

针对柴油机曲轴轴承声发射(Acoustic Emission,AE)信号中裂纹特征信息微弱,易与噪声混淆等问题,在K-SVD字典对信号稀疏的基础上,提出一种均值信号改进的K-SVD字典的滑动轴承AE信号去噪算法。重组均值信号和扩展到K-SVD信号矩阵中,在实现... 详细信息

针对柴油机曲轴轴承声发射(Acoustic Emission,AE)信号中裂纹特征信息微弱,易与噪声混淆等问题,在K-SVD字典对信号稀疏的基础上,提出一种均值信号改进的K-SVD字典的滑动轴承AE信号去噪算法。重组均值信号和扩展到K-SVD信号矩阵中,在实现K-SVD稀疏AE信号矩阵的同时,稀疏提取均值信号的裂纹信号,利用K-SVD处理前、后的均值信号提取其中的本底信号,并采用模糊加权均值滤波器对本底信号进行去噪,去除与裂纹信号混淆的噪声,最后根据信号矩阵、稀疏的裂纹信号和去噪后的本底信号得到低信噪比的AE信号。试验结果表明,所提算法有效去除了AE信号中易与裂纹信号混淆的噪声,使故障特征更加明显,成功刻画了滑动轴承不同摩擦状态间的变化。

关键词：滑动轴承声发射 K-SVD 均值信号

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汽车-道路相互作用研究进展

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机械工程学报 2021年第12期57卷 1-17页

作者：杨绍普张俊宁路永婕李韶华石家庄铁道大学省部共建交通工程结构力学行为与系统安全国家重点实验室石家庄050043 石家庄铁道大学交通运输学院石家庄050043 石家庄铁道大学机械工程学院石家庄050043

回顾汽车-道路相互作用的研究历程和主要研究内容,分析汽车系统动力学、轮胎动力学和路面结构动力学三个研究领域之间的关系,分别从车辆的随机振动与道路友好性悬架、轮胎-路面接触动力学和动载荷下道路结构动力学三个层面对研究进展进... 详细信息

回顾汽车-道路相互作用的研究历程和主要研究内容,分析汽车系统动力学、轮胎动力学和路面结构动力学三个研究领域之间的关系,分别从车辆的随机振动与道路友好性悬架、轮胎-路面接触动力学和动载荷下道路结构动力学三个层面对研究进展进行综述,提出汽车-道路相互作用研究中存在的问题和未来的发展方向。当前汽车-道路相互作用研究多集中于单一领域或者三个领域简单叠加,忽略或简化了汽车-道路之间相互作用、互相约束的复杂动态耦合关系,但是要满足车辆更高的控制精度和动力学性能优化,需要更多的考虑汽车-道路之间的相互作用关系。对于胎路接触关系,现有的研究多是以路面的特定参数来描述轮胎自身的滞回特性,考虑轮胎与路面之间的动态耦合特性需要更深一步研究。简单的路面不平度模型对路面的形貌描述不够,制约着车-路相互作用的研究,开展路面形貌特征的提取、描述和重构仍很重要。车辆运动控制的实现和控制器的设计多依赖于质心的动态响应和路面附着状况,汽车-轮胎-地面瞬态耦合机理及路面参数的高精度快速识别将是极具理论难度与工程应用的研究。此外,轮毂电机在新一代智能电动汽车的应用,改变了汽车底盘构型及载荷分布,考虑路面随机激励、电机激励及车路耦合激励的综合作用研究车-路相互作用及智能控制也是一项具有挑战性的科学问题。

关键词：车-路相互作用胎-路动态摩擦道路友好性悬架三维路面谱路面参数识别

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一种在脉冲噪声环境下的最大相关熵目标直接定位算法

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系统工程与电子技术 2023年第9期45卷 2651-2658页

作者：毛毅段永胜黄中瑞张峻宁国防科技大学电子对抗学院安徽合肥230037

无源定位技术在水面舰艇定位、海域监测、地面非法入侵等领域都具有重要应用价值。为了解决在不一致的脉冲噪声环境下的定位问题,本文使用α-稳定分布对脉冲噪声建模。在此基础上,应用最大相关熵准则,提出了最大相关熵目标直接定位算法... 详细信息

无源定位技术在水面舰艇定位、海域监测、地面非法入侵等领域都具有重要应用价值。为了解决在不一致的脉冲噪声环境下的定位问题,本文使用α-稳定分布对脉冲噪声建模。在此基础上,应用最大相关熵准则,提出了最大相关熵目标直接定位算法。仿真结果表明,该算法在强脉冲噪声环境下具有较好的定位精度,并且算法核长参数的选取不依赖于脉冲噪声的先验信息;在脉冲噪声不一致条件下,所提算法仍然能够实现对目标的精确定位。

关键词：目标直接定位脉冲噪声最大复相关熵噪声不一致

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