基于LMD基本尺度熵的AP聚类滚动轴承故障诊断*

摘要：针对滚动轴承聚类故障聚类模式识别方法中需要预先设定聚类数目问题,提出了一种基于局部均值分解（Local Mean Decompoeiton, LMD）与基本尺度熵（Base Scale Entropy, BSE）的相邻传播（Affinity Propagation, AP）滚动轴承聚类故障诊断方法。该方法首先使用LMD模型将滚动轴承的不同状态振动信号分解为若干乘积函数（Production Function, PF）。其次使用BSE计算前3个PF的熵值（BSE1-BSE3）,并将其作为AP的输入进行滚动轴承的故障模式识别。最后实验结果表明在不需要划分聚类中心个数的前提条件下AP聚类模型对滚动轴承的故障划分效果较好。 关键词：局部均值分解;基本尺度熵;滚动轴承;故障诊断;AP聚类算法     

一种基于盲信号提取的同频干扰抵消算法

为了抵消数字通信中的同频干扰,提出了一种基于单信道盲信号提取算法。不同于现有的盲信号提取盲分离模型,本文的模型除了利用数字信号过采样特性,还充分考虑了载波频率以及信道噪声的影响。并结合调制信号的恒模特性,提出了基于广义峭度的恒模盲信号提取算法。最后通过实验结果证实算法的有效性和稳定性。     

Multi-laboratory evaluation of a PCR method for detection of ruminant DNA in commercial processed animal proteins

In 2013, the European Union (EU) allowed the inclusion of non-ruminant processed animal proteins (PAP) in fish feeds. Plans also exist to allow non-ruminant PAP in poultry and pig feeds but to keep intraspecies recycling forbidden (e.g. poultry to poultry or pig to pig). However, due to the fear of transmissible spongiform encephalopathy (TSE), PAP from ruminant species remains illegal to use in feeds. To ensure feed safety, nations across Europe need to safeguard that commercial fish feeds do not contain PAP from ruminant species. In this work we report a multi-laboratory study on the detection of ruminant PAP in commercial PAP feed ingredients. A total of 19 non-ruminant PAP, provided by the European Fat Processors and Renderers Association (EFPRA), were analyzed for ruminant content with the European Union Reference Laboratory (EURL)-validated PCR assay by three labs and compared to the result obtained with an immunoassay-based method (MELISA-TEK). Ruminant PAP was detected in five of the 19 non-ruminant PAP samples with both methods, but there were methodological and multi-laboratory differences for the PCR method. Compared to the results with the EU-reference laboratory, 3 false-negatives were found by the two other laboratories. We speculate that the discrepancies seen for some of the samples determined with the PCR method rely on the homogenization and grinding step, which is not described in detail in the EURL Standard Operating Procedure (SOP), shift in the normal distribution of Ct-values near the cut-off of the PCR method, or PCR inhibition. In conclusion, this study demonstrates the presence of ruminant DNA in commercially available non-ruminant PAP by use of two methods for the detection of PAP in commercial feed ingredients, and highlights the importance of thorough homogenization prior to DNA extraction and assessment of normal distribution of Ct-values for successful PCR detection at low ruminant DNA contamination levels.     

Al-5％Pb合金的超声波分散效果

以A1-5％Pb合金为对象，研究了超声波工艺参数对Pb溶质分布的影响。利用背散射电子成像（BSE）扫描对试样进行了检测，测试了试样的硬度及磨损性能。实验结果表明：在铸造条件下，采用超声波处理能够有效抑制Al-Pb合金的溶质偏析。超声波功率对Pb溶质分散性有直接的影响，功率过大或功率过小都达不到令人满意的分散效果；过短的处理时间达不到Pb溶质分散的目的，而过长的处理时间会使Pb粒子发生聚集，只有采用合适的处理时间才能达到理想的分散效果。Pb溶质分散得细小均匀可以有效地提高硬度及耐磨性。     

Application of a polymerase chain reaction (PCR) method as a complementary tool to microscopic analysis for the detection of bones and other animal tissues in home‐made animal meals

A polymerase chain reaction (PCR) method was compared with a variation of the official microscopic technique (Directive 98/88/EC) for the detection in animal meals of cereals (wheat and corn) and animal parts (bone, feathers, meat, liver, fat and blood). Microscopy successfully detected animal bones in raw feeds with a sensitivity of 1 g kg^?1, while the sensitivity of the PCR method was in the range of 5–10 g kg^?1. Microscopy also allowed the detection of animal bones and feathers in feeds processed at 115 and 133 °C but failed to detect other animal materials. The PCR method successfully detected cereals (wheat and corn) as well as meat, bone, liver, fat and feathers after processing at 115 °C for 20 min. Heating at 133 °C under overpressure (autoclave) conditions resulted in more intense DNA fragmentation and lower DNA extractability. Nevertheless, bone and liver, as well as wheat and corn in home‐made animal meals, were successfully detected even after heating at 133 °C for 20 min. Copyright © 2004 Society of Chemical Industry     

Electrolyte infiltration in phosphazene-based dye-sensitized solar cells

We report here a study of phosphazene polymer and oligomer electrolyte infiltration into high surface area titanium dioxide electrodes and its effect on the performance of dye-sensitized solar cells. The effects of different cell assembly procedures on the electrochemical properties are examined, as well as the infiltration of electrolytes based on poly[bis(2-(2-methoxyethoxy)ethoxy)phosphazene] (MEEP), hexakis(2-(2-methoxyethoxy)ethoxy)cyclotriphosphazene (MEE trimer), and a linear short chain analogue into conventional titanium dioxide electrode mesoporous (nanosphere) films, microcolumns and nanowires. The effects of temperature, co-solvents, and the order of addition of the electroactive components are found to affect both the conductivity of the electrolytes and the electrochemical performance of the cells. Cross-sectional scanning electron microscopy (SEM) imaging is employed to examine the degree of electrolyte infiltration into the nanostructured electrodes as a function of filling conditions. Using these techniques, conditions are identified for achieving a high degree of pore filling by the three electrolyte systems. Increased power conversion efficiency is obtained when iodine is introduced after the heating and evacuation procedures required for maximum infiltration.     

CuCr预合金粉压坯时效性能

应用雾化方法制备了Cu-0.5Cr、Cu-0.8Cr和Cu-1.5Cr的3种预合金粉末,经压制成型后对其进行时效处理。测量了时效后样品的显微硬度,并对经200℃×480 m in时效后的Cu-0.5Cr合金压坯进行了背散射电子分析。结果表明,经大量变形后,合金在时效过程中产生了较为复杂的变化。在200℃时效初期,回复过程占主导地位,合金硬度有所下降;之后析出占主导地位,合金硬度又有所上升;而在500℃时效时,Cr的析出强烈推迟了再结晶的发生。结果还表明,Cr从Cu基体中的析出规律为先通过扩散在合金中的缺陷较高的部位形成富集区,再形核长大。     

学习巴登管理经验 提升企业管理水平

3年前南钢集团开始引进素以“高效率钢厂”著称的德国巴登公司的先进管理经验。通过对巴登公司管理经验的引进，使南钢的各项工作都有了较大的改善，许多技经指标有了显著进步，从而达到了管理出效益的目的。     

Multi‐walled carbon nanotubes decorated by platinum catalyst nanoparticles—Examination and microanalysis using scanning and transmission electron microscopies

Carbon nanotubes (CNTs) decorated with platinum (Pt) nanoparticles (NPs) have been characterized using a cold field‐emission scanning electron microscope (SEM) and a high resolution field‐emission transmission electron microscope (TEM). With this particular composite material, the complementary nature of the two instruments was demonstrated. Although the long CNTs were found to be mostly bent and defective in some parts, the nucleation of Pt occurred randomly and uniformly covered the CNTs. The NPs displayed a large variation in size, were sometimes defective with twins and stacking faults, and were found to be faceted with the presence of surface steps. The shape and size of the NPs and the presence of defects may have significant consequences on the activity of the Pt catalyst material. Also, thin layers of platinum oxide were identified on the surface of some NPs.     

Experimental study of the interfacial transition zone (ITZ) of model rock-filled concrete (RFC)

Rock-filled concrete (RFC), a new type of concrete that was developed mainly for large scale concrete construction, has a different casting process than conventional concrete: large rocks are piled into the formwork first, then self-compacting concrete (SCC) is poured in and fill the voids of the rock skeleton under gravity due to its high flowability. One of the key issues about RFC lies in its large interfaces between the SCC and rocks. In this paper, laboratory-scale model RFC consisting of coarse aggregates (simulating rocks) and cement grout (simulating SCC) was cast to simulate RFC in construction. The effects of different factors (aggregate size, rheology of cement grout, etc.) on the properties of the interfacial transition zone (ITZ) between cement paste and aggregates of model RFC were investigated using Backscatter Electron (BSE) and nanoindentation techniques. Furthermore, by comparing the results of BSE and nanoindentation at identical regions, the relationship between porosity and elastic modulus was found to agree well with empirical formulas, bridging the microstructure with the mechanical properties of concrete.