一种新的基于声信号的故障分类算法

提出采用相空间重构与高斯混合模型相结合的方法,利用声信号对设备进行故障分类.此方法首先将一维声信号时间序列进行相空间重构,在高维相空间展示各故障状态下的动力学特性,然后通过最大期望值算法建立相空间的高斯混合模型,最后采用贝叶斯分类算法进行故障的识别.从齿轮故障试验台上采集常见齿轮故障的声信号并进行分类实验,验证了该方法的有效性.     

基于四分位偏差分形维与高斯混合模型的故障识别算法研究

针对四分位偏差分形维对信号幅值大小和分布敏感的缺点,提出了适用于故障识别的四分位偏差分形维改进算法,将四分位偏差分形维及其截距组成特征向量,应用高斯混合模型进行故障模式描述(QDFD-GMM),并采用贝叶斯分类器进行故障识别.分别采用QDFD-GMM和基于重构相空间与高斯混合模型算法(RPS-GMM)对同一组故障齿轮振动信号进行分类,结果表明:QDFD-GMM具有更高的识别率和运算速度,具有更强的鲁棒性.     

基于递归定量分析与高斯混合模型的齿轮故障识别

针对递归图只能对信号进行定性分析,不利于其深入应用的缺点,应用递归定量分析方法对各种故障模式振动信号进行定量分析.采用确定率和层流率组成齿轮故障识别的特征向量,并结合高斯混合模型实现齿轮故障模式识别.以齿轮故障实验台上所测取的实验数据为对象,分别采用Re-substitution检验法,Jackknife检验法和Independent dataset检验法对提出的方法和RBF人工神经网络分类算法进行检验.结果表明,递归定量分析与高斯混合模型相结合应用于齿轮故障模式识别具有更高的识别率.     

基于加权相空间重构降噪及样本熵的齿轮故障分类

提出了一种基于加权相空间重构降噪及样本熵的齿轮故障分类方法,给出了加权相空间重构降噪及样本熵的原理及计算公式.该方法将一维的时间序列重构到高维的相空同,通过区分吸引子在高维空间的不同的属性与特征,对原始信号进行加权相空间重构降噪,再计算降噪后信号的样本熵从而实现对齿轮故障信号的分类.对该方法进行了仿真与实验研究,结果表明,降噪后的信号有效地抑制了噪声对实验结果的影响,使得样本熵能够对齿轮不同的工作状态进行有效区分.     

基于双层相空间相似度的滚动轴承故障模式与故障程度的综合辨识

提出了一种基于双层相空间相似度分析算法结构,应用于滚动轴承故障类型和故障程度的综合辨识。该算法第一层结构中,对测试数据和样本数据进行相空间重构(PSR),得到在拓扑意义下等价的相空间,然后使用滑动窗截取数据段,采用归一化互相关函数(NCC)进行相空间相似度分析,实现轴承故障类型的分类;在第二层结构中,以已知不同故障程度数据之间的相空间相似度(PSS)为特征训练SVR结构,实现对故障程度的跟踪。实验信号分析结果表明,该方法能有效对轴承故障类型和故障程度进行综合辨识。与传统方法的对比表明该方法在准确性上有了一定的提高。     

排列熵与核极限学习机在齿轮故障诊断中的应用

针对齿轮故障难提取和极限学习机(extreme learning machine,ELM)隐层节点数需要人为设定,致使齿轮故障分类模型准确度低、稳定性差的问题,提出基于核极限学习机(kernel extreme learning machine,K-ELM)的齿轮故障诊断方法。首先,将测得信号经经验模态分解(empirical mode decomposition,EMD)处理后得到一系列IMF本征模式分量,并提取各分量的排列熵(permutation entropy,PE)值组成高维特征向量集;然后利用高斯核函数的内积表达ELM输出函数,从而自适应确定隐层节点数;最后,将所得高维特征向量集作为K-ELM算法的输入建立核函数极限学习机齿轮故障分类模型,进行齿轮不同故障状态的分类辨识。实验结果表明:与SVM、ELM故障分类模型相比,核函数ELM滚动齿轮故障诊断分类模型具有更高的准确度和稳定性。     

相关熵和双谱分析齿轮故障诊断研究

相关熵为高斯、非高斯噪声处理的一种有效方法,针对强高斯噪声和非高斯噪声干扰下齿轮故障诊断问题,提出了一种基于相关熵和双谱的齿轮故障诊断方法。该方法综合利用高斯核函数和不完全 Cholesky 分解算法计算信号的相关熵,然后再计算相关熵的双谱,根据相关熵的双谱特征识别齿轮故障。通过不完全 Cholesky 分解算法计算信号的相关熵,不仅大大压缩了数据量,突出了齿轮故障特征,而且提高了计算效率。通过仿真和齿轮磨损故障振动信号分析结果表明：强背景噪声会造成传统双谱故障诊断方法失效,而基于相关熵和双谱分析的齿轮故障诊断方法,能在强噪声干扰背景中提取齿轮的故障特征准确识别齿轮故障,其性能优于传统双谱和小波变换域双谱,为一种有效的齿轮故障诊断方法。     

四分位偏差分形维及其在齿轮故障识别中的应用

介绍了用于非平稳、非线性信号的四分位偏差分形维算法，并通过仿真实例验证了此计算方法的准确性。针对齿轮振动信号的非平稳、非高斯、非线性特点，将四分位偏差分形维用于齿轮故障分类，结果表明此方法能很好地区分齿轮故障模式。以四分位偏差与相应的截距为特征量进行聚类，能更好地区分齿轮的各种故障模式。可将其用于在线故障识别。     

基于相空间重构与独立分量分析的局部独立投影降噪算法

针对故障分析信号中存在噪声问题,提出一种将相空间重构与独立分量分析相结合的局部独立投影降噪算法。其中相空间重构的目的在于从高维相空间中恢复混沌吸引子,独立分量分析能够找到信号的主流形,选择邻域是为了将特征相近的相点结合在一起。使用该方法对正弦仿真信号和Lorenz仿真信号进行降噪处理,结果表明局部独立投影降噪算法的降噪效果与局部独立分量分析算法降噪效果接近,但优于全局投影降噪算法。运用该方法对低速重载轴承振动信号进行分析,准确判断出轴承故障。     

延时矢量方差算法及其在齿轮故障识别中的应用

提出了利用时间序列的延时相空间重构，采用延时矢量方差及替代数据的时间序列非线性的检验方法，并将该方法应用于设备故障信号的非线性检验与故障识别。数值实验结果表明，延时矢量方差法是一种有效、直观的非线性检验与故障识别方法，对噪声信号具有很强的鲁棒性，对非线性信号具有很高的敏感性。采用该方法对齿轮振动信号进行非线性检验与故障识别，结果与实际情况相符。     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.