共查询到20条相似文献,搜索用时 125 毫秒
1.
Effective vibration recognition can improve the performance of vibration control and structural damage detection and is in high demand for signal processing and advanced classification.Signal-processing methods can extract the potent time-frequency-domain characteristics of signals;however,the performance of conventional characteristics-based classification needs to be improved.Widely used deep learning algorithms(e.g.,convolutional neural networks(CNNs))can conduct classification by extracting high-dimensional data features,with outstanding performance.Hence,combining the advantages of signal processing and deep-learning algorithms can significantly enhance vibration recognition performance.A novel vibration recognition method based on signal processing and deep neural networks is proposed herein.First,environmental vibration signals are collected;then,signal processing is conducted to obtain the coefficient matrices of the time-frequency-domain characteristics using three typical algorithms:the wavelet transform,Hilbert-Huang transform,and Mel frequency cepstral coefficient extraction method.Subsequently,CNNs,long short-term memory(LSTM)networks,and combined deep CNN-LSTM networks are trained for vibration recognition,according to the time-frequencydomain characteristics.Finally,the performance of the trained deep neural networks is evaluated and validated.The results confirm the effectiveness of the proposed vibration recognition method combining signal preprocessing and deep learning. 相似文献
2.
INFLUENCE OF DAMPING MODELS ON DYNAMIC ANALYSES OF A BASE-ISOLATED COMPOSITE STRUCTURE UNDER EARTHQUAKES AND ENVIRONMENTAL VIBRATIONS 下载免费PDF全文
Structural design simultaneously governed by earthquakes and environmental vibrations has received a lot of attention in recent years.Base-isolated composite structures are typically used in the above-mentioned structural design.The corresponding analysis involves validating structural safety under earthquakes and human comfort under environmental vibrations through a time-history analysis.Thus,a reasonable damping model is essential.In this work,the representatives of viscous damping model and rate-independent damping model,namely the Rayleigh damping model and uniform damping model,were adopted to investigate the influence of damping models on the time-history analysis of such structural designs.The energy dissipation characteristics of the above-mentioned damping models were illustrated via a dynamic test of recycled aggregate concrete specimens.A case study was performed on a base-isolated steelconcrete composite structure.The dynamic responses under the excitation of earthquakes and environmental vibrations were compared using different damping models.The uniform damping model was found to be more flexible than the Rayleigh damping model in dealing with excitations with different frequency components.The uniform damping model is both theoretically advantageous and easy to use,demonstrating its potential in dynamic analysis of structures designed simultaneously governed by earthquakes and environmental vibrations. 相似文献
3.
回顾茅台酒的发展历史,作为一个具有悠久历史的品牌,作为民族酒业的杰出代表,国酒茅台几十年的辉煌业绩让每一个国人为她而骄傲。但它的巨大品牌优势同时也吸引了众多制假、售假者的目光。这些不法之徒大肆制售假茅台,严重侵害了企业和消费者的合法权益。对此,茅台酒厂投入了大量人力、物力、财力,在打假、防伪方面取得了很大的成效。据茅台打假办提供的信息表明,他们每年花在防伪打假上的各种费用达上亿元。总结茅台打假防伪的经验无疑对保护知名品牌是有益的。 相似文献
4.
5.
6.
公共交通优先发展,不仅体现落实科学发展观的客观要求,也是建设资源节约型、环境友好型社会的重要举措。但孝感市公共交发展存在公交车辆总量不足、公交车辆道路运行难、公交车辆运营调度技术手段和票务方式落后等问题。于是,研究深入调查分析产生这些问题的原因并提出相应的对策与建议,这有其一定的现实指导意义。 相似文献
7.
Developing an electrically conductive and corrosion-resistant coating is essential for metal bipolar plates of polymer electrolyte membrane fuel cells(PEMFCs). Although enhanced corrosion resistance was seen for Cr coated stainless steel(Cr/SS) bipolar plates, they experience a quick decrease of through-plane electrical conductivity due to the formation of a porous and low-conductive corrosion product layer at the plate surface, thus leading to an increase in interfacial contact resistance(ICR). To tackle this issue, the multilayer Cr coatings were deposited using the magnetron sputtering with a remote inductively coupled oxygen plasma(O-ICP) in the present study. After the O-ICP treatment, a Cr oxide layer(Cr O*) is formed on the specimen surface. The Cr O*/Cr/SS has a remarkably lower stable corrosion rate(iss) than that of the native Cr oxides(Cr On/Cr/SS). Compared with Cr On/Cr/SS, the excellent performance of Cr O*/Cr/SS is attributed to a denser and thicker surface layer of Cr O* with Cr being oxidized to its highest valence state,Cr(VI). More importantly, the through-plane electrical conductivity of the specimens treated by the optimized O-ICP decreases much slowly than Cr On/Cr/SS and thus, the increament of ICR of Cr O*/Cr/SS after the potentiostatic polarization test is considerably smaller than that of Cr On/Cr/SS, which is benefited from the reduced issthat mitigates the deposition of corrosion products and hinders further oxidation of Cr coating. Therefore, Cr O*/Cr/SS proves to be a well balanced trade-off between corrosion resistance and through-plane electrical conductivity. The results of this study demonstrate that O-ICP treatment on a conductive metal coating is an effective strategy to improve the corrosion resistance and suppress the increase of ICR over the long-term polarization. The technique reported herein exhibits its promising potential application in preparing corrosion resistant and electrically conductive coatings on metal bipolar plates to be used in PEMFCs. 相似文献
8.
<正>2013年,上海质监局对该市22批次学生服产品进行抽检,发现6个批次产品存在质量问题,而供应多家学校的某服装公司生产的校服产品存在致癌威胁;2014年,美国第一夫人米歇尔访华引发中国校服"丑到爆"的讨论;2015年,广东东莞又曝出2180元的"天价校服"事件。从质量到款式,再到价格,关于国内校服的争论可谓年复一年,从未停止。中国校服如此备受质疑,却又总是难以加快前进的脚步,使其背后标准的缺失问题也逐渐暴露。中小学生校服问 相似文献
9.
10.
11.
12.
13.
非线性粘弹性桩耦合运动中的混沌分析 总被引:1,自引:1,他引:1
研究轴向周期载荷作用下非线性粘弹性桩纵横向耦合运动中的混沌运动。桩体材料满足Leaderman非线性粘弹性本构关系和近似的非线性几何关系,考虑桩体发生纵横向运动的耦合,得到的方程为耦合的非线性偏微分一积分方程;利用Galerkin方法将方程简化并进行数值计算,揭示非线性粘弹性桩的混沌运动和分岔等动力学行为。 相似文献
14.
纵向振动粘弹性桩的分叉和混沌运动 总被引:1,自引:3,他引:1
研究了轴向周期载荷作用下非线性粘弹性嵌岩桩纵向振动的混沌运动。假定桩和土体分别满足Leaderman非线性粘弹性本构关系和线性粘弹性本构关系,得到的运动方程为非线性积分-偏微分方程;利用Galerkin方法将方程简化,并进行了数值计算。数值结果表明纵向振动的非线性粘弹性桩可以通过准周期分叉的方式进入混沌运动。 相似文献
15.
An asymptotic approach is proposed to investigate nonlinear parametric vibration of axially accelerating viscoelastic strings. The string is constituted by the Kelvin model with the material time derivative. Both the Mote model and the Kirchhoff model of transverse motion are analyzed via the asymptotic approach in principal parametric resonance. The modulation equation is derived from the solvability condition. Closed-form expressions of the amplitudes and the existence conditions of steady-state responses are solved from the modulation equation. Numerical results are presented to highlight the effects the initial stress, the parameters in the Kelvin model, and the axial speed fluctuation amplitude on the amplitudes and the existence conditions of steady-state responses. 相似文献
16.
研究非线性轴向运动黏弹性Rayleigh梁因速度周期变化产生的亚谐波共振。轴向运动速度在平均速度附近做简谐周期性脉动。通过取物质导数的Kelvin本构关系描述Rayleigh梁的黏弹性。运用多尺度近似解析方法,构建轴向运动Rayleigh梁的非线性偏微分方程的可解性条件,分析参数振动稳态响应的振幅与扰动速度频率关系。并运用微分求积方法直接离散非线性Rayleigh梁的控制方程,以验证近似解析方法分析。通过数值算例,分析了系统参数对稳态响应曲线的影响。 相似文献
17.
18.
This paper analytically and numerically investigates the nonlinear vibration in parametric and internal resonances of in-plane
accelerating viscoelastic plates subjected to plane stresses. An approximate nonlinear plate theory was developed under the
Kirchoff assumptions. The in-plane translating speed is characterized as a simple harmonic variation about the constant mean
axial speed. The governing equation with the associated boundary conditions is derived from the generalized Hamilton principle
and the Kelvin constitutive relation. The method of multiple scales is applied to establish the solvability conditions in
principal parametric and internal resonances. The steady-state responses are predicted in three possible patterns: trivial,
single-mode, and two-mode solutions. The stabilities of the steady-state responses are determined based on the Routh-Hurwitz
criterion. The effects of the mean in-plane translating speed, the in-plane translating speed fluctuation amplitude, the viscosity
coefficient, and the nonlinear coefficient on the steady-state responses are examined. The differential quadrature schemes
are developed for the two-dimensional full plate model and the one-dimensional reduced plate model to solve the nonlinear
governing equations numerically. The numerical calculations confirm the approximate analytical results regarding the trivial
and single-mode solutions of the steady-state responses. 相似文献
19.
Nonlinear torsional vibrations of thin-walled beams exhibiting primary and secondary warpings are investigated. The coupled nonlinear torsional–axial equations of motion are considered. Ignoring the axial inertia term leads to a differential equation of motion in terms of angle of twist. Two sets of torsional boundary conditions, that is, clamped–clamped and clamped-free boundary conditions are considered. The governing partial differential equation of motion is discretized and transformed into a set of ordinary differential equations of motion using Galerkin’s method. Then, the method of multiple scales is used to solve the time domain equations and derive the equations governing the modulation of the amplitudes and phases of the vibration modes. The obtained results are compared with the available results in the literature that are obtained from boundary element and finite element methods, which reveals an excellent agreement between different solution methodologies. Finally, the internal resonance and the stability of coupled and uncoupled nonlinear modes are investigated. This study can be a preliminary step in the understanding of complex dynamics of such systems in internal resonance excited by external resonant excitations. 相似文献
20.
微分求积法处理轴向变速黏弹性梁混杂边界条件 总被引:1,自引:1,他引:0
给出了一种利用微分求积法处理非线性轴向变速黏弹性梁的混杂边界条件的方法。利用微分求积法数值求解具有混杂边界轴向变速黏弹性梁的控制微分方程,将混杂边界条件直接引入到控制微分方程高阶导数的微分求积解权系数矩阵中。使用这种方法研究了非线性轴向变速黏弹性梁主参数共振的稳态幅频响应,并对算例的微分求积解和解析近似解做了比较。 相似文献