基于小波包与Hilbert解调谱的矿用齿轮箱故障诊断

介绍了小波包分解与Hilbert解调技术,利用小波包分解可以突出能量集中的频段,然后利用Hilbert解调谱提取其故障特征.结果表明小波包与Hilbert解调谱相结合可以有针对性地提取矿用齿轮箱的低频调制故障特征,从而实现矿用齿轮箱的精密故障诊断.     

像差修正拼接法测量非球面精度的评定

针对用子孔径干涉像差修正拼接法测量非球面的拼接精度问题,提出了一种基于t分布统计的拼接精度分析评定方法.根据测量原理及拼接模型特点,利用残差分析对模型进行回归诊断,使用因变量预测算法和t分布统计模型对拼接精度进行估计与分析.实验结果显示:按t分布评定拼接结果的扩展不确定度为0.362 3λ(0.229 μm),而常规的系统误差检验方法评定拼接结果的扩展不确定度为0.234 μm,两种方法结果基本一致,表明基于t分布统计的方法在保证评定结果准确度的前提下,克服了比较分析法的不确定性,解决了正态分布统计法中置信系数k不能反映子样标准差可靠性对置信概率的影响问题.     

多分辨率能量波动-近似熵方法的设备故障诊断研究

结合小波包分解(WPT)方法和近似熵(ApEn)方法,提出一种多分辨率能量波动-近似熵方法的设备故障诊断技术.首先利用小波包分解将振动信号分解为各频率成分正交、无冗余和无遗漏的子信号,然后对子信号进行能量波动检验,给出故障的存在性诊断;对于存在故障的子信号进行近似熵计算,根据近似熵值的大小,分析信号的复杂性程度,即故障的严重程度.仿真及工程验证结果表明,提出的方法可以有效诊断设备故障的存在性及严重程度.     

HiFIT – Technische Entwicklung und Anwendung

Das Verbundprojekt REFRESH bot in den vergangenen drei Jahren eine ideale Plattform für die theoretische und experimentelle Weiterentwicklung des HiFIT (high frequency impact treatment)‐Verfahrens. So konnten sowohl die Behandlungsparameter an umfangreichen Schweißproben optimiert als auch ein industrietaugliches Gerätedesign unter Einbeziehung zahlreicher Anwendungsfälle aus der Praxis der Industriepartner entwickelt werden. Effizienz, Ergonomie und die Qualitätssicherung standen bei der Entwicklung im Vordergrund. Die Beurteilung der Anwendbarkeit des Verfahrens und die Anwendung selbst sollten im Sinne einer allgemeinen Qualitätssicherung und zur Quantifizierung des zu erwartenden Behandlungserfolgs von geschultem Personal durchgeführt werden. Letzteres gilt nicht nur im Speziellen für das HiFIT‐Verfahren, sondern generell für alle Nachbehandlungsverfahren. Hinter dem Markennamen HiFIT steht ein ganzheitliches Lösungskonzept mit rechnerischen Analysetools, Nachbehandlungswerkzeugen, Schulung und Consulting zur effizienten Steigerung der Betriebsfestigkeit neuer und bereits im Einsatz befindlicher Schweißkonstruktionen. HiFIT – Technical development and application. In the past three years the HiFIT technology for application on welded parts has been investigated in the REFRESH project. Many treatment parameters have been tested. Using prototype devices a lot of experience has been gained by treatment of several parts in cooperation with the project partners. The design of the HiFIT device is optimized for industrial application where efficiency, ergonomics and quality assurance are the main topics. An application benchmark of HiFIT and the treatment should be done only by specially trained employees. This restriction is not only HiFIT specific. The trademark HiFIT means a solution for improvement of fatigue strength of new and cyclic pre‐damaged welded structures. The solution contains assessment of fatigue strength, treatment devices, training and consulting.     

Analysis of crossed van't Hoff metal hydride based heat pump

In this paper, the operating feasibility of a single-stage metal based hydride heat pump (SS-MHHP) working on the principle of crossed van't Hoff line concept is presented. The performance of the system is predicted by solving the unsteady, two-dimensional mathematical model in an annular cylindrical configuration employing two different hydride alloy pairs, namely, V_0.846Ti_0.104Fe_0.05/Fe_0.9Mn_0.1Ti and V_0.855Ti_0.095Fe_0.05/MmNi_4.7Al_0.3 (regeneration alloy/refrigeration alloy). The influences of heat source (T_H) and refrigeration (T_C) temperatures on the amount of hydrogen transferred between the paired reactors, coefficient of performance (COP) and specific cooling power (SCP) of the crossed van't Hoff SS-MHHP system are studied. Within the selected ranges of operating temperatures, the COP of the crossed van't Hoff SS-MHHP is about 60% higher than the conventional single-stage MHHP. The optimum operating temperatures of V_0.846Ti_0.104Fe_0.05/Fe_0.9Mn_0.1Ti and V_0.855Ti_0.095Fe_0.05/MmNi_4.7Al_0.3 combinations are found to be 373/303/291 K and 400/303/283 K (heat source/heat sink/refrigeration temperatures), respectively. At the optimum operating temperatures, the COP and SCP of the V_0.846Ti_0.104Fe_0.05/Fe_0.9Mn_0.1Ti and V_0.855Ti_0.095Fe_0.05/MmNi_4.7Al_0.3 combinations are 0.89 and 30.8 W/kg of total mass and 0.86 and 30.3 W/kg of total mass, respectively.     

800MPa级DP钢冲压成形及裂纹扩展机理

通过冲压弯曲试验研究800MPa级DP钢的极限拉伸,采用扫描电子显微镜观察分析钢板的微观组织及动态拉伸过程,探讨其微观组织与其稳机理的关系。结果表明,DP800钢断口为剪切型断裂。凸模圆角半径较小时,拉深弯曲断裂是由于折弯角过小而在凸模圆角处折弯断裂;凸模圆角半径较大时,冲压弯曲断裂由于受到板料延伸率的限制,在材料流动受限的凹模圆角附近断裂。DP800的断口均分布着大量韧窝的韧性断裂,其裂纹扩展机理是微裂纹,主要产生于铁素体或马氏体/铁素体相界面,主裂纹沿两相界面或贯穿铁素体而继续扩展。     

Sequential Change-Point Detection Methods for Nonstationary Time Series

We present two new spectral-based methods for detection of changes in autocorrelation structure in a continuous-valued time series in an online process monitoring setting. Our methods are based on the idea that changes in the autocorrelation structure are reflected by changes in the Fourier or wavelet-based spectrum and can be detected by comparing estimated spectra of adjacent blocks of the series. To be effective for slowly changing spectral structure, the methods are extended to allow information from more than one past block to be used in determining whether a change has occurred, in such a way as to minimize computational burden. Through simulation, we evaluate the performance of our methods and find that they can provide reliable and timely detection of changes in covariance structure in an online monitoring framework. We illustrate the methods using electroencephalogram traces (brain waves) and run-time computer performance metrics.     

基于三端法的HHT行波故障测距研究

输电线行波故障定位的技术关键在于提高捕捉故障行波波头信号到达时间的精确度以及行波波速度的确定。小波变换(Wavelet Transform,WT)是目前主要采用的波头识别算法,而希尔伯特-黄变换(HilbertHuang Transform,HHT)作为分析非平稳和非线性信号一种强大的工具值得深入研究,文章提出了基于三端测距法的HHT行波测距方法。采用Simulink建立输电线路仿真模型,通过haar、db4小波和HHT分析对比,结果表明HHT能更有效地提高故障定位精度,且克服了小波变换需要选择小波基函数和分解尺度的缺点。     

沙特阿拉伯3条5000t/d熟料水泥生产线工程技术特点

中国中材国际工程股份有限公司在沙特阿拉伯承建了多条大型熟料生产线EPC工程,其中的三条5000t/d熟料水泥生产线.分别于2007年5月到12月先后投产,至发稿时,大部分已通过了生产考核.由于技术标准、原燃料、建厂理念、环境条件和配置水平的不同,使这三条线的工艺方案设计、装备控制配置、环境安全考虑等等方面,与国内同类工程相比具有众多的特有性能.文章整体介绍了这三条线的工艺方案(包括主机配置、主要储库设计);重点分析了这三条线的技术特点;简要介绍了这三条线的投产运行情况.同时,就这三个项目的进一步优化等问题,进行了反思和探索.     

Pitting mechanism on an austenite stainless steel nanocrystalline coating investigated by electrochemical noise and in-situ AFM analysis

The pitting corrosion behavior of an austenite stainless steel with polycrystalline (PC) and nanocrystalline (NC) microstructure in 3.5% NaCl solution was investigated by electrochemical noise (EN) and in-situ atomic force microscopy (AFM) under anodic potential. The power spectral density (PSD) and wavelet transform have been employed to analyze the EN data. The pitting corrosion resistance of the NC coating was much higher than that of the PC alloy, with different pitting mechanisms observed for both specimens; a slow metastable pit generation and healing for the PC alloy and a fast metastable pit initiation and death for the NC coating. There was good conformity between the EN and the in-situ AFM analysis. The pitting corrosion mechanism has been discussed according to the EN analysis and the in-situ AFM observations.