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滚动轴承出现损伤时,采集的振动信号呈非平稳性,采用一般的时域和频域分析方法不能准确提取出振动信号的故障特征。根据小波包多分辨、精细化的分解特性,提出一种基于小波包能量谱与主成分分析(PCA)方法的滚动轴承故障诊断算法。将振动信号进行小波包分解,得到重点频率段信息的能量谱,提取能量谱作为特征向量;利用PCA方法对特征向量降维并减小噪声信号的干扰,获得增强的故障特征;利用层次聚类方法和改进的模糊c均值聚类算法对不同类型的滚动轴承故障进行识别,两种聚类方法都准确地识别出了不同的故障类型。实例验证结果表明,所提方法能够有效地提取振动信号中的有用故障特征,实现轴承故障类型的精确诊断。 相似文献
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基于局域波降噪和双谱分析的自动机故障诊断研究 总被引:3,自引:3,他引:0
特征提取是机械故障诊断的关键,能否准确地提取出反映机械设备工作状态的特征信息,直接影响到故障诊断的准确性和早期预报的可靠性。自动机表面的振动信号成分复杂,除了含有丰富的零部件运动状态信息外,也存在着大量的噪声成分。只有有效地去除干扰信息,才能对信号做出正确地评估和分析。自动机表面的振动信号具有明显的短时冲击特性,是一种典型的非高斯、非线性信号。高阶谱分析,特别是双谱分析,在处理非高斯信号和识别非线性系统故障等方面具有一定的优越性。将局域波理论和双谱分析相结合,对自动机振动信号进行降噪处理和分析,结果表明其应用在自动机故障诊断中具有较好的识别效果。 相似文献
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针对双谱的特点,提出一种新的雷达信号脉内特征参数提取方法.对接收到的信号首先提取双谱幅度谱并简化为二维特征,然后求取该二维特征的复杂度特征中的盒维数和信息维数.由于不同信号的双谱区别大且对高斯噪声不敏感,因此提取的盒维数和信息维数可分性强、稳定度高,仿真验证了新脉内特征参数的优越性. 相似文献
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为更好地利用振动信号对枪械自动机的裂纹故障进行诊断,提出基于振动信号多分形特征的故障诊断方法。该方法利用Wavelet Leader 来估计振动信号的多分形谱,通过6个特征量描述多分形谱的形态特征以实现多分形谱的降维,并使用基于Mahalanobis距离的分类器对不同的裂纹故障进行分类。应用该方法对某12.7 mm高射机枪自动机闭锁机构的裂纹故障进行了诊断,诊断正确率达到了82.5%,验证了将振动信号的多分形特征用于自动机裂纹故障诊断的可行性。 相似文献
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在毫米波雷达系统中,信噪比对作用距离的影响很大;要满足探测及识别目标对信噪比的要求,就制约了雷达系统的作用距离。为改善雷达自动控测识别目标的能力,放宽对接收机信噪比的要求,本文在对含操信号的双谱特性进行分析的基础上,提取了含有目标信号双谱相位信息的特征矢量;它不仅包含了丰富的目标回波信息,而且对噪声不敏感。实验结果表明,在信噪比很低时,信号双谱波形变化不大,特征矢量仍很稳定,大大降低了目标识别对雷达系统信噪比的要求,从而提高了毫米波雷达的灵敏度及作用距离。 相似文献
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Expert systems aimed at the general design of projectiles can implement a series of intelligent designs, such as the design of HE shell, the scheme expounded and proved, the emulation analysis and calculation, etc. Aiming at the product design feature, the expert system adopts the object-oriented knowledge representation and all kinds of inference control engines to describe and reason the relevant knowledge regarding the product through the microcomputer. It embodies the foundation of emulation analysis and simulated manufacturing of the shell. It makes use of the method that knowledge expression is combined with condition of inference to carry out the overall design and emulation and reference.The paper gives the ways through which the functions can be achieved, gives the modularization of reference and the design methods of systematization, puts forward the method of knowledge expression and working interface, and supplies a platform for similar products of the shell category that can be quickly designed. 相似文献
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In order to study the effect of rotation on the combustion in the underwater vehicle, a two-phase turbulent combustion process is described with Reynolds stress turbulence model, eddy-dissipation turbulent combustion model, P-1 radiation model and particle tracking model of liquid. The flow in the rotating combustion chamber is simulated at two different working speeds, 0 r/min and 1 000 r/min by Fluent software. The temperature, gas velocity, static pressure of wall and fuel concentration are computed and compared. The results show that the combustion in rotating combustor is faster and more effective. 相似文献
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This paper attempts to do a research on the development of software defined radio(SDR) based on software communication architecture(SCA). Firstly, SCA is studied and a whole reference model of SCA3.0 core framework (CF) is realized; Secondly, an application-specific FM3TR waveform is implemented on the platform of common software based on the reference model; Thirdly, from the point of view of real-time performance and software reuse, tests and validations are made on the above realized CF reference model and FM3TR waveform. As a result, the SCA-compliant SDR has favorable interoperability and software portability and can satisfy the real-time performance requirements which are not too rigorous. 相似文献
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In mechanical, hydraulic and electronic systems, the determination of system parameters is often challenging because liquid parameters often change significantly, due to variations in working and environmental conditions. Therefore, it is of significant practical importance to identify those parameters through experimental procedures. A systematic approach to identifying parameters in the valve controlling cylinder system of hydraulic manipulators is provided. It first derives the transfer function of the system, and then uses P control of PID control to predict system parameters. The predicted parameters are further validated using PID control. The prediction through simulation using MatLab language is utilized, which agrees well with experimental results. 相似文献
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By using the ATV module of MSC. ADAMS, the dynamic simulation of recoil response of tank gun is analyzed.How the recoil force affects the bodywork and the suspension during gun firing, as well as the changing status of the gun muzzle‘s velocity are gained. All results and analyzing methods are offered for the designing basis of optimizing tank vehicle-gun match. The constructive exploration is beneficial to improving the general capability of tank. 相似文献
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The controllable suspension system can improve the performances of off-road vehicles both on road and cross-country. So far, four controllable suspensions, that is, body height control, active, semi-active and slow-active suspensions, have been developed. For off-road vehicles, the slow-active suspension and the semi-active suspension which have controllable stiffness, damping and body height are more appropriate to use. For many years, some control methodologies for controllable suspension systems have been developed along with the development of modern control theory, and two or more original control methods are integrated as a new control method. Today, for military or civilian off-road vehicles, the R&D of controllable suspension systems is ongoing. 相似文献
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Protocols for key management are compared and evaluated from the point of view on mobile ad hoe networks (MANET). The issues of fault-tolerance and efficiency of key distribution protocols for group communications in MANET are addressed. Most key distribution protocols existing today are primarily designed for wlre-line networks. These protocols either fail to work as intended or cannot work at all when they are applied to the demanding environment of MANET. Parameters and performance of different protocols are analyzed, and then a fiat is given out, on which new protocols or existing ones are designed and modified, so that they can be robust, scalable and efficient in MANET. 相似文献
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Finite Element Analysis of Fretting Behavior Between an Engine Cylinder Block and a Main Bearing Cap
The finite element analysis of the fretting behavior between a cylinder block and a main bearing cap is presented. The stresses, relative fretting slip, fretting friction work parameter W and crack initiation location parameter G on the fretting contact surface of the cylinder block are obtained and analyzed. It shows that the fretting fatigue problem of the cylinder block can be quantitatively explained by W or G. The effects of pretightening force, friction factor and material combination of the cylinder block and the main bearing cap are studied. The computational results indicate that the fretting fatigue of the cylinder block can be allayed by increasing the elastic modulus of the cylinder block, but not by changing the other two factors. 相似文献
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Electromagnetic armor is a new conceptual combat vehicle technology, which improves remarkably the defensive capability and maneuverability of vehicles. The authors present definitely to apply the electromagnetic theory to analyze the electromagnetic armor. Based on electromagnetics, the experienced expression of projectile and the physical model of PEMA (passive electromagnetic armor) are obtained when electric current flows through the system, and a computer sim- ulation is given. 相似文献
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Through analyzing the kinematics of the hydraulic manipulator operating system, according to the rules for set-ing up the D-H coordinate system, the generalized coordinate of the manipulator system is established. The rotating and moving joints are selected from the mechanism as joint variables. Each generalized transformation matrix of joints is worked out. The kinematics equation at the finger end of the manipulator is calculated. The obverse solution for the manipulator is gained. The geometrical operating parameters and primary technical specification of the manipulator system are simulated through the computer. The simulative result has shown that the manipulator operating system meets the working task requirements. This research provides theoretical basis for optimizing structural parameters of the manipulator operating. So it also is justified the feasibility for mechanical manipulators to be used in the engineering equipment platform of the hydraulic excavator. 相似文献