钻井泵振动可视化分析方法研究

钻井泵是石油钻机系统的核心动设备之一,其故障诊断的难点在振动共性的寻找。本文以钻井泵传动系统作为研究对象,提出了一种基于振动可视化分析的系统工作状态特征的提取方法。首先分析了振动可视化技术相比于传统分析方法的优势,以及系统振动可视化分析的可行性;随后进行有效性分析。通过振动可视化技术补充和完善常规监测手段所得到的振动信息,同步反映设备关键测点在时间和频率上的变化,以此作为泵体整体故障诊断的依据。分析结果表明,振动可视化分析方法能够全面而准确地将系统状态特征提取出来,为最终故障模式准确匹配提供有效依据。     

机械设备状态监测及智能诊断系统的研究

阐述了机械设备状态监测及智能诊断技术在现代维修体系下的重要性,归纳总结了传统振动诊断技术,分析了机械设备故障诊断技术的发展趋势,阐明了智能诊断技术是未来高精度、高速复杂机械系统可靠运行、正确维护、维修的重要保障     

空分装置风机振动故障的分析与处理

介绍空分装置风机机组振动故障的处理过程及频谱分析方法的具体应用,利用频谱分析方法对状态监测的结果进行研判,找到了造成风机振动故障的主要原因.通过检修及更换新的轴承座后,运行至今未发现故障,达到了预期效果.     

基于小波分析和矩不变量的转子故障量化特征提取研究

为解决旋转机械智能诊断中缺少量化特征值的问题,提出了一种基于小波分析和矩不变量的量化特征提取新方法。在对实验转子振动信号进行小波分析的基础上,采用了灰度图来对连续小波分解系数进行表达,并提取出灰度图的7个矩不变量作为描述振动信号状态特征的量化特征值系列。分析表明,该方法所提取的转子信号量化特征值系列,能够有效地区分出几种典型故障间的差别。     

基于虚拟技术的齿轮故障智能诊断研究

利用LabVIEW图形化编程语言开发了信号分析与处理、信号特征提取和故障诊断三大模块。信号特征提取由小波包分解来实现,故障诊断通过神经网络完成,小波包分解提取的齿轮振动信号各频段能量特征值作为神经网络的输入向量。以模拟故障实验台获取的齿轮典型故障振动信号训练神经网络,利用训练好的神经网络对齿轮进行故障诊断,实验结果表明：所开发的齿轮故障智能诊断系统能有效识别齿轮故障,较好地将虚拟技术应用于故障诊断领域。     

石油化工转动设备的振动故障分析

浅述振动产生的原因及其分析方法,从转动设备常见的振动故障类型和振动故障的分析步骤这两个方面进行石油化工转动设备常见的振动故障分析。     

压差发电涡轮叶片振动响应的长度分形故障特征提取与诊断

为了对压差发电机组中涡轮进行故障监测与故障诊断,对涡轮压差发电机组的叶片振动响应进行了分析,并将其作为涡轮运行状态分析的特征量。应用有限元分析方法,建立了550 KW涡轮发电机组的动力学模型,通过计算与调试过程的模态分析,分别获得整个机组的固有频率和振型,并比较验证了工程中实际机组的合理性。用锤击法测得涡轮叶片正常状态和偏心故障下的振动加速度响应信号,应用非线性动力系统的长度分形维数理论,计算其长度分形维数,并将其作为涡轮叶片偏心故障诊断识别的特征量。研究结果表明,该方法能有效识别涡轮机叶片正常工作状态和偏心故障的状态,及其偏心位置和偏心量大小。     

振动监测技术在齿轮机构故障诊断中的应用

在机电设备故障诊断中,振动监测技术是最常用的方法。以轧机减速器齿轮机构故障诊断为例,采用频谱分析方法,从振动幅值的变化及时域波形特点分析故障频率特征,从而查明故障原因,为维修提供重要依据。     

往复压缩机气阀振动信号的二阶循环谱特征提取

往复压缩机气阀振动信号具有典型的循环平稳性,循环平稳理论正是处理这类信号的有效工具,在研究二阶循环自相关及其傅里叶谱理论的基础上,对其主要特性进行了信号仿真研究,并将其应用到往复压缩机故障特征提取中,对2D12往复压缩机气阀在正常阀片和有缺口故障阀片两种状态下的实验数据进行了分析,结果表明二阶循环谱能够准确、有效地提取出往复压缩机气阀故障特征。     

转动设备振动监测方法及案例分析

为了准确诊断转动设备振动故障,解决振动问题,通过实际案例介绍了怎样选用振动监测方法和如何进行故障诊断、处理,总结了转动设备常见故障的振动分析方法。实践表明,不平衡、不对中、松动、流体扰动、动静碰摩、滚动轴承故障基本可以通过频谱、波形、相位及高频解调谱分析几种振动分析方法得到较准确的诊断。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.