共查询到20条相似文献，搜索用时 31 毫秒
1.
陈广锋 《西安文理学院学报》2010,(4):54-57
爆震的检测对于发动机的安全性和使用寿命有着重要的意义.首先建立了发动机缸体的雷达回波信号模型,分析了正常燃烧和爆震现象发生时缸体振动信号的微多普勒特征,并利用SPWV时频分析方法提取了该信号的微多普勒特征,最后通过仿真验证了利用微多普勒特征检测爆震现象的实时性和有效性. 相似文献
2.
Study of engine noise based on independent component analysis 总被引：1，自引：0，他引：1
HAO Zhi-yong JIN Yan YANG Chen 《浙江大学学报(A卷英文版)》2007,8(5):772-777
Independent component analysis was applied to analyze the acoustic signals from diesel engine. First the basic prin-ciple of independent component analysis (ICA) was reviewed. Diesel engine acoustic signal was decomposed into several inde-pendent components (ICs); Fourier transform and continuous wavelet transform (CWT) were applied to analyze the independent components. Different noise sources of the diesel engine were separated, based on the characteristics of different component in time-frequency domain. 相似文献
3.
针对常规降噪方法应用于柴油机缸盖振动信号降噪时,自适应差且需要根据噪声环境人为调整参数的问题,在传统EEMD算法基础上提出一种改进的EEMD降噪算法,并将其应用于柴油机缸盖振动信号处理。首先对原始信号进行预处理,其次利用总体经验模态分解（EEMD）算法在非线性、非平稳信号处理时的自适应特性,分解原始信号得到各阶本征模态分量,经Savitzky-Golay平滑滤波,再将噪声占主导的高频分量进行阈值去噪,最后得到干净的本征模态分量进行重构。仿真实验和实测结果表明,在输入信号12dB的多种输入信号工况下,改进EEMD算法去噪后信噪比为17.1,比现有去噪方法提升14%。 相似文献
4.
A hybrid of ensemble empirical mode decomposition and empirical mode decomposition (EEMD-EMD) is introduced to diagnose the valve-slap vibration signal,which is relative to the dominant combustion knock vibration signal given out by a diesel engine around the top dead center (TDC).The time-frequency representations of intrinsic mode functions (IMFs) decomposed by EEMD-EMD are obtained by adaptive generalized S transform (AGST).A type 493 diesel engine was used for the experiment,and the result indicates that the valve-slap of the diesel engine is serious,and the vibration frequencies are higher than the combustion knock.With EEMD-EMD-AGST approach,the valve-slap can be identified by the vibration analysis of the diesel engine. 相似文献
5.
Fault diagnosis of valve clearance in diesel engine based on BP neural network and support vector machine 总被引：1，自引：0，他引：1
Based on wavelet packet transformation(WPT), genetic algorithm(GA), back propagation neural network(BPNN)and support vector machine(SVM), a fault diagnosis method of diesel engine valve clearance is presented. With power spectral density analysis, the characteristic frequency related to the engine running conditions can be extracted from vibration signals. The biggest singular values(BSV)of wavelet coefficients and root mean square (RMS)values of vibration in characteristic frequency sub-bands are extracted at the end of third level decomposition of vibration signals, and they are used as input vectors of BPNN or SVM. To avoid being trapped in local minima, GA is adopted. The normal and fault vibration signals measured in different valve clearance conditions are analyzed. BPNN, GA back propagation neural network (GA-BPNN), SVM and GA-SVM are applied to the training and testing for the extraction of different features, and the classification accuracies and training time are compared to determine the optimum fault classifier and feature selection. Experimental results demonstrate that the proposed features and classification algorithms give classification accuracy of 100%. 相似文献
6.
《天津大学学报(英文版)》2015,(4)
Targeting the non-stationary characteristics of diesel engine vibration signals and the limitations of singular value decomposition(SVD) technique, a new method based on improved local mean decomposition(LMD), SVD technique and relevance vector machine(RVM) was proposed for the identification of diesel valve fault in this study. Firstly, the vibration signals were acquired through the vibration sensors installed on the cylinder head in one normal state and four fault states of valve trains. Secondly, an improved LMD method was used to decompose the non-stationary signals into a set of stationary product functions(PF), from which the initial feature vector matrices can be formed automatically. Then, the singular values were obtained by applying the SVD technique to the initial feature vector matrixes. Finally, slant binary tree and sort separability criterion were combined to determine the structure of multi-class RVM, and the singular values were regarded as the fault feature vectors of RVM in the identification of fault types of diesel valve clearance. The experimental results showed that the proposed fault diagnosis method can effectively extract the features of diesel valve clearance and identify the diesel valve fault accurately. 相似文献
7.
For a single cylinder engine, the total unbalanced inertial forces occur in the engine block, which results in engine’s vibration
and deteriorated noise. In order to eliminate the unbalanced forces, counterweight and primary balance shaft should be attached
to the cylinder block so that engine durability and ride comfortability may be further improved. Traditionally one third of
connecting rod assembly’s mass is treated as reciprocating mass, and two thirds as rotating mass when designing balance mechanism.
In this paper, a new method based on the multibody dynamics simulation is introduced to separate the reciprocating mass and
rotating mass of connecting rod assembly. The model consists of crankshaft, connecting rod, piston and the simulation is performed
subsequently. According to the simulation results of the main bearing loads, the reciprocating mass and rotating mass are
separated. Finally a new balance mechanism is designed and simulation results show that it completely balances inertial forces
to improve the engine’s noise vibration and harshness performance. 相似文献
8.
以Pro/ENGINEER Wildfire作为工作平台,对发动机汽缸进行三维模型设计,并完成零件的装配,然后利用工程分析模块Mechanism对汽缸进行动态仿真、运动学和动力学分析,以实现高效、精确、低成本的最优化产品设计。 相似文献
9.
Acoustic signals from diesel engines contain useful information but also include considerable noise components. To extract information for condition monitoring purposes, continuous wavelet transform (CWT) is used for the characterization of engine acoustics. This paper first reviews CWT characteristics represented by short duration transient signals. Wavelet selection and CWT are then implemented and wavelet transform is used to analyze the major sources of the engine front's exterior radiation sound. The research provides a reliable basis for engineering practice to reduce vehicle sound level. Comparison of the identification results of the measured acoustic signals with the identification results of the measured surface vibration showed good agreement. 相似文献
10.
Acoustic signals from diesel engines contain useful information but also include considerable noise components.To extract information for condition monitoring purposes, continuous wavelet transform (CWT) is used for the characterization of engine acoustics. This paper first reviews CWT characteristics represented by short duration transient signals.Wavelet selection and CWT are then implemented and wavelet transform is used to analyze the major sources of the engine front's exterior radiation sound. The research provides a reliable basis for engineering practice to reduce vehicle sound level.Comparison of the identification results of the measured acoustic signals with the identification results of the measured surface vibration showed good agreement. 相似文献
11.
张树忠 《福建工程学院学报》2018,(6):516-519
针对风力发电机关键部件齿轮箱故障频率高、诊断难的问题,开发了包含传统时频域分析和现代分析模块的故障诊断系统。该系统对所采集的振动信号进行了小波去噪、小波包分解并重构后得到各频段能量占比的特征向量,将该特征向量输入到Back Propagation（BP）神经网络模型进行振动信号与正常或各故障状态之间映射,从而智能识别运行状态。应用Matlab和Labview开发系统,输入齿轮箱的4种典型运行状态进行验证,结果表明,所设计的系统可较好地对风机齿轮箱的故障进行诊断。 相似文献
12.
基于定子电流信号进行异步电机故障诊断时,转子断条和匝间短路故障特征频率分量常常被电流的基频分量淹没,利用小波变换的能量谱对其进行诊断十分必要.考虑到小波分析在时域、频域都具有表征信号局部特征的能力,能通过时频窗的灵活变换来突出信号的不同频率成分;同时还有用小波处理非平稳信号的优越性,计算出各频带所占能量,进而获取能量分布的故障特征.实践表明,通过上述分析并从能量分布的角度出发,可以快速、准确地诊断出电机故障,诊断效果好于傅里叶分析;同时也提供了一种思路,为电机故障在线实时诊断提供了理论依据. 相似文献
13.
降噪处理是分析结构振动信号、提取特征参数、研究损伤识别方法的基础,核独立分量分析(KICA)采用的核方法为结构振动信号的降噪处理提供了新的方法;通过对比KICA与其他算法降噪后信号的HHT边际谱,验证了KICA对低阻尼钢框架结构标准损伤模型降噪的优良性能,特别是提高了对结构安全至关重要的低频振动部分的能量估计的准确度。 相似文献
14.
用模糊函数表示超声信号,以解决特征提取时不同中心频率和不同到达时间的超声信号的预处理问题,并为信号分类提供时频特征。提出采用Karhunen-Loeve(K-L)变换提取信号的模糊平面特征,并对特征的分类能力进行了分析。实验结果表明模糊函数能有效去除信号的中心频率和到达时间的差异,用K-L变换提取的模糊平面特征能在低维空间有效地描述超声信号,并能获得较好的分类效果。 相似文献
15.
A novel time-frequency domain interference excision technique is proposed. The technique is based on adaptive biorthogonal local discrete cosine transform (BLDCT). It uses a redundant library of biorthogonal local discrete cosine bases and an efficient concave cost function to match the transform basis to the interfering signal. The main advantage of the algorithm over conventional transform domain excision algorithms is that the basis functions are not fixed but can be adapted to the time-frequency structure of the interfering signal. It is well suited to transform domain compression and suppression of various types of interference. Compared to the discrete wavelet transform (DWT) that provides logarithmic division of the frequency bands, the adaptive BLDCT can provide more flexible frequency resolution. Thus it is more insensitive to variations of jamming frequency. Simulation results demonstrate the improved bit error rate (BER) performance and the increased robustness of the receiver. 相似文献
16.
The high-rise frame structure has become more and more widespread, like its damage from the complication of the environment. The traditional method of damage detection, which is only suitable for the stationary signal, does not apply to a high-rise frame structure because its damage signal is non-stationary. Thus, this paper presents an application of the short-time Fourier transform (STFT) to damage detection of high-rise frame structures. Compared with the fast Fourier transform, STFT is found to be able to express the frequency spectrum property of the time interval using the signal within this interval. Application of STFT to analyzing a Matlab model and the shaking table test with a twelve-story frame-structure model reveals that there is a positive correlation between the slope of the frequency versus time and the damage level. If the slope is equal to or greater than zero, the structure is not damaged. If the slope is smaller than zero, the structure is damaged, and the less the slope is, the more serious the damage is. The damage results from calculation based on the Matlab model are consistent with those from the shaking table test, demonstrating that STFT can be a reliable tool for the damage detection of high-rise frame structures. 相似文献
17.
A new lighting and enlargement on phase spectrogram （PS） and frequency spectrogram （FS） is presented in this paper. These representations result from the coupling of power spectrogram and short time Fourier transform （STFT）. The main contribution is the construction of the 3D phase spectrogram （3DPS） and the 3D frequency spectrogram （3DFS）. These new tools allow such specific test signals as small slope linear chirp, phase jump case of musical signal analysis is reported. The main objective is to and small frequency jump to be analyzed. An application detect small frequency and phase variations in order to characterize each type of sound attack without losing the amplitude information given by power spectrogram 相似文献
18.
发动机气缸盖是较易发生疲劳破坏的发动机零件之一,其机械疲劳强度与螺栓预紧力之间存在关系。利用Solidworks建立气缸的简化模型,导入Workbench中进行静力学分析：在Workbench中建立两个不同的载荷环境,利用组合求解功能对螺栓预紧力和气缸盖受到气缸内气体的最高爆发压力进行线性组合,完成非比例载荷的疲劳寿命计算,得到不同螺栓预紧力下的气缸盖疲劳寿命曲线,由此获知螺栓预紧力和气缸盖疲劳寿命之间的关系,这为合理选择螺栓预紧力提供了依据。 相似文献
19.
局部放电信号是非平稳性信号,具有时变频率。时频分析是分析和处理非平稳时变信号的有力工具,将时频分析技术应用于局部放电信号的分析与处理,能清楚地揭示信号的时变频谱特性,有利于对信号的特征提取,为局部放电信号的模式识别提供了一个更为准确、可靠的新方法。 相似文献
20.
研制了具有油孔的金属液压减振器 ,它由油缸和油缸底部的弹簧组成 .考虑液体的动力学和连续条件 ,建立了液压减振器力学模型和动力学方程 ,研究了液体的动力刚度和液压机座的传递能力 .计算结果表明 ,所提出的液压机座具有优良的减振性能 .本文对于液压机座减振器的分析方法可应用于减振器的设计 ,并且所设计的金属液压减振机座可应用于实际减振工程中 相似文献