齿轮箱故障诊断中小波技术的应用

针对齿轮箱故障振动信号的特点,分析了采用傅里叶变换对齿轮故障诊断信号分析技术的不足,提出了采用小波变换的方法提取齿轮箱故障振动信号;通过实例分析,阐明了应用小波变换技术对齿轮箱故障诊断的有效性.     

小波神经网络在齿轮箱故障诊断中的应用

介绍了小波神经网络的基本概念及其构造，并针对齿轮箱故障的复杂性，综合利用小波函数的特点，构造了用于齿轮箱故障诊断的小波网络，对齿轮箱的状态进行判别，实现故障诊断．实验结果表明，小波神经网络在故障诊断领域具有良好的实用性．     

基于小波降噪和BP神经网络的风力发电机组齿轮箱故障诊断研究

针对风电机组齿轮箱故障频发这一现象,为改善设备性能,提高其利用率,采用基于小波降噪和BP神经网络相融合进行风电机组齿轮箱故障诊断与研究的方案.首先利用小波对采样数据降噪,然后输入小波神经网络中进行诊断,以准确地识别齿轮箱中常见的故障,结果表明该方案具有可行性.并结合风电场应用实例,证明了方案的可行性,为提高风力发电机组齿轮箱的稳定性提供了一种有效方法.     

小波分析在故障诊断中的应用

简述小波分析的数学原理和小波分析在故障诊断中的应用机理，并以钻井泥浆泵为例，分析了小波分析在故障诊断中的应用。结果表明，用小波降噪的方法先对泵阀信号进行处理后再进行特征提取和故障诊断变得容易；用小波进行泵阀信号的消噪可很好地保存瞬态冲击信号中的尖锋和突变部分。     

小波分析在系统辨识中的应用

目前，小波在信号分析、图像处理、计算机视觉与识别、医学成像与诊断、地震勘探数据处理、大型机械的故障诊断等很多领域得到了广泛的应用。随着小波分析理论的发展和成熟，小波分析在系统辨识领域中的应用越来越多，尤其是在非线性系统辨识中的应用潜力越来越大。本文对小渡分析的主要特点进行了介绍，并论述了小渡分析在系统辨识中的应用。     

信号瞬变成分检测与提取及其在故障诊断中的应用

研究基于小波变换的信号瞬变成分检测与提取方法及其在机械故障诊断中的应用 .在分析信号的连续小波变换的模极大值理论的基础上 ,指出连续小波变换系数的模与信号瞬变成分的关系 ;通过分析小波函数的性质 ,分析小波函数对信号的连续小波变换的影响 ;在信号瞬变特征的提取过程中 ,提出基于门限值的特征重建方法 .将该方法应用于齿轮箱振动信号中瞬变成分的检测与重建 .结果表明基于连续小波变换方法能有效检测到信号中的瞬变成分 ,瞬变成分的重建结果有效地表示了机械的故障状态 .     

小波分析及其在电机中的最新应用

阐述了小波分析及其特点，对小波分析在发电机故障诊断、电机故障诊断以及电机测试中的最新应用进行了综述，并指出了目前小波分析在电机中应用中存在的问题和发展趋势。     

小波分析在旋转机械故障诊断中的应用

简述小波分析的数学原理和小波分析在故障诊断中的应用机理，并以透平压缩机组为例，分析了小皮分析在故障诊断中的应用。用小波进行信号降噪的方法是，先对机组轴承径向报动信号进行处理后再进行特征提取，使故障诊断过程变得容易，很好地保存了瞬态信号的尖峰和突变部分。     

粒子群优化算法在齿轮箱振动信号去噪中的应用

 以振动频谱分析和粒子群优化算法为主要理论依据,以风力涡轮机齿轮箱为例,提出一种基于一维加速搜索算法和粒子群优化的齿轮箱振动信号去噪方法。利用一维加速搜索算法缩减搜索范围,应用粒子群优化算法提升优化效果,对切比雪夫带通滤波器和Morlet小波滤波器的设计参数进行优化,并对齿轮箱故障振动信号进行滤波处理。仿真实验结果表明,此方法能够实现快速有效滤波去噪,适用于齿轮箱实时故障诊断的研究,具有一定的理论研究价值和实践应用价值。     

基于双树复小波分解的风机齿轮箱故障诊断

风机齿轮箱振动信号具有非平稳、非高斯特性,多种模式混叠和复杂的传递路径使得故障信息微弱完全淹没在噪声之中.针对故障特征提取的难题,将双树复小波变换引入振动信号分析,提出了一种新的工业风力发电机齿轮箱故障诊断方法.首先对风机齿轮箱振动信号进行双树复小波分解,然后计算各频带分量的峭度值,利用峭度筛选故障敏感分量.最后对故障敏感分量进行频谱分析提取故障特征频率.实验结果表明:双树复小波变换可将复杂信号分解为不同频带分量,抑制平移敏感性和频率混叠.与传统离散小波变换相比,能有效抑制虚假频率出现并准确提取故障特征.本文提出的方法已成功用于风力发电机工业运行监测并准确诊断多种类型的齿轮箱故障.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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