管道振动故障三维识别方法

针对传统的管道单通道故障诊断存在的局限性,提出将全信息小波包技术和支持向量机技术相结合的管道振动故障识别。用小波包变换对三通道信号分别分解,用能量法求出分解后各频带信号对应的能量,并构建三维全信息能量特征向量,作为支持向量机分类器的训练样本和测试样本。经验证,训练后的分类器能够对管道振动进行识别和诊断,并且提高了故障识别的效率和精度。     

基于LabVIEW的倒频谱与包络谱分析在风电机组齿轮箱故障诊断中的应用

风力发电机组的齿轮箱许多故障信息以调制形式存在于振动信号之中,在此利用LabVIEW强大的信号分析功能对齿轮箱振动信号进行分析,开发出基于倒频谱与包络谱分析的齿轮箱故障诊断系统。试验结果表明:倒频谱与包络谱分析可以有效诊断出齿轮箱的故障信息。     

基于形态滤波和HHT的滚动轴承故障特征提取

应用形态滤波和HHT提取滚动轴承振动信号故障特征。通过形态组合滤波对信号进行预处理,对预处理后的信号进行EMD分解,把信号分解为若干个IMF的和,之后计算IMF的希尔伯特能量谱,提取振动信号的故障特征频率。本算法能够较准确地提取出滚动轴承振动信号的故障特征频率,为滚动轴承振动检测与故障诊断研究提供参考。     

自适应小波降噪的泵机组故障诊断

泵机组故障诊断的难点在于信号特征向量的提取,而故障特征往往淹没在复杂的噪音中。本文利用自适应小波函数对采集到的振动信号进行降噪,滤掉了无关的噪声信息,根据振动能量的分布,对降噪过的信号进行四层小波包分解,提取出的特征向量分布明显。最后将分类特征向量输入神经网络进行训练,测试的结果证明,该方法识别精度高、速度快,具有良好的应用前景。     

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。     

设备故障的振动及冲击综合诊断

本从运动学、频谱信号和振动能量三方面分析了机器运行中振动和冲击两类故障的区别；介绍了冲击型故障的检测原理，并给出了综合运用振动、冲击两种技术进行检测和分析的方法及应用实例。     

旋转机械故障诊断与预测方法及其应用研究

旋转机械最重要的部件是转子系统以及轴承,由于机械在运行过程中长期处于高速、满负荷运行状态,经常会出现故障。本文基于转动信号的在线诊断以及实时诊断等特点,对频谱分析对于非线性振动信号故障特征的提取存在的不足展开分析,深入探讨旋转机械故障诊断与预测方法及其应用研究及旋转机械故障诊断及预测方法发展方向研究,希望能给相关工作人员提供帮助。     

高速转子故障模拟实验研究

在分析高速转子的典型故障机理及危害的基础上,利用多功能柔性转子实验台及PL302双通道数据采集器等测试设备对高速旋转机械的不对中、不平衡及基础松动等故障进行模拟,并根据振动信号分析故障的振动特征及规律,为旋转机械的状态监测及故障诊断提供了依据.     

塑料光纤传感器在烟草机械故障诊断的应用研究

基于塑料光纤传感器在烟草机械的故障监测诊断方法。通过塑料光纤传感器采集了烟草机械轴承的状态信号,研究了振动信号的时域信号和频域信号。结果表明:内圈故障和外圈故障对轴承带来的冲击最大,振动幅值相对于滚子故障轴承更高。均值、峰值指标和波形指标不适用于轴承的故障状态识别,峰值、脉冲指标和裕度指标适合识别内圈故障和外圈故障的轴承,有效值和峭度指标适合区分内圈故障、外圈故障、滚子故障和正常状态的轴承。正常状态轴承信号谐波分量最少,内圈故障和滚子故障轴承信号的谐波分量最多。滚子故障轴承信号的谐波分量幅值最小,外圈故障轴承信号的谐波分量幅值最大。     

泵站机组的故障诊断

自来水行业对泵站机组的安全与经济性能的要求越来越高,迫切地认识到备品可靠性是满足新市场需求的重要保证,也是参与竞争的必要前提。但是机组容量的不断加大,导致了其系统和结构的复杂性不断增加。机组结构的复杂性与机组工作环境的特殊性提高了水泵故障诊断的难度。振动信号是判断水泵故障信息的主要来源,利用振动信号进行故障判断是最常用的方法。如不了解故障机理,可通过机组振动信号展开相关分析处理,对水泵常见故障预测与诊断等进行的研究。随着故障诊断技术的发展,必将使故障诊断越来越准确、越来越快速,应用也更加广泛。     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

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.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、环氧树脂、不饱和聚酯树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.