阶次包络谱在轴承故障诊断中的应用

旋转机械的升降速过程包含丰富的状态信息,因而旋转机械的升降速过程对于旋转机械的故障诊断具有独特的价值.将常规的阶次分析技术与包络谱相结合,提出基于阶次包络谱的齿轮箱故障诊断方法.首先对齿轮箱升降速瞬态信号进行时域采样,再对时域信号实行等角度重采样,转化为角域平稳信号,最后对角域重采样信号进行包络谱分析,就可提取轴承的故障特征.通过对轴承内圈、外圈故障实验信号的分析,表明该方法能有效诊断轴承的故障.     

多层异种钢复合波纹管与SUS304接管的焊接

根据多层波纹管产品特点，通过试验制定了多层异种钢复合波纹管一层耐蚀层为IN800，基层为4呈SUS316的膨胀节与SUS304接管的焊接工艺。经工艺评定和产品性能试验证明，按该工艺焊接的接头可以满足设计和使用要求。     

Sediment delivery ratio and its uncertainties on flood event scale:Quantification for the Lower Yellow River

Sediment delivery ratio(SDR)for fluvial rivers was formulated with sediment rating curve.The observed data of SDR on flood event scale of the Lower Yellow River(LYR)were adopted to examine the formulation and to calibrate the model parameters.A regression formula of SDR was then established and its 95%prediction interval was accordingly quantified to represent its overall uncertainties.Three types of factors including diversity of the incoming flow conditions,river self-regulation processes,and human activi...     

非定比传动机械的计算阶次分析

研究非定比传动旋转机械非稳态信号的分析方法。由于可以避免传统频谱分析的“频率模糊”现象,阶次分析方法常被用来分析转速不稳定的机械信号。对传动比不确定的机械系统进行信号分析时,由于系统中存在不同的轴频,单一的阶次分析将难以满足要求,需进行多轴阶次分析。文中介绍多轴阶次分析的计算方法,对等时间间隔采样的信号,利用插值算法实现角域重采样,并在此基础上实现计算阶次分析。实例证明该方法可以在阶次域内将与不同轴频相关的信号进行分离,有效识别系统工况。     

2008年下半年国内手机市场运行情况分析

1 市场运行情况 1.1 产业增速前高后低 受全球金融危机影响,中国手机产业发展速度明显放缓,结构调整继续深化.2008年,产业增速呈现前高后低态势.     

Phase change and optical band gap behavior of Ge-Te-Ga thin films prepared by thermal evaporation

The amorphous Ge_11.4Te_86.4Ga_2.2 chalcogenide thin films were prepared by thermal evaporation onto chemically cleaned glass substrates. Properties measurements include X-ray diffraction (XRD), Scanning electron microscopy (SEM), Differential scanning calorimetry (DSC), Four-point probe and VIS-NIR transmission spectra. The allowed indirect transition optical band gap and activation energy of samples were calculated according to the classical Tauc equation and Kissinger's equation, respectively. The results show that there is an amorphous-to-crystalline phase transition of Ge_11.4Te_86.4Ga_2.2 thin film. The investigated film has high crystallization temperature (∼200 °C) and activation energy (2.48 eV), indicating the film has good amorphous stability. The sheet resistance of the crystalline state is ∼10 Ω/and the amorphous/crystalline resistance ratio is about 10⁵. Besides, a wide optical band gap (0.653 eV) of Ge_11.4Te_86.4Ga_2.2 is obtained, indicating that the material possesses a low threshold current from amorphous-to-crystalline state for phase-change memory application.     

钛硅分子筛TS-1动态过滤的研究

对钛硅分子筛TS 1微粉催化剂应用动态过滤技术 ,在动态旋叶压滤机上进行了过滤性能的研究 ,得到了过滤速率随时间的变化规律 ,并分析了操作压力对过滤速率的影响。为了结合实际工业生产的要求 ,对过滤介质进行了再生实验。该研究为TS 1微粉催化剂的过滤分离提供了一个可行的方法 ,为确定适宜的操作条件及工业应用提供了实验依据     

环己醇脱氢制环己酮催化剂的研究进展

评述了由环己醇脱氢制己内酰胺生产的重要中间体环己酮催化剂的研究与实际应用的进展。重点叙述了目前国内外工业应用催化剂的组成,制备方法,并对其优缺点进行了评述。     

Facile hydrothermal synthesis and characteristics of B-doped TiO2 hybrid hollow microspheres with higher photo-catalytic activity

The boron doped titanium oxide hybrid hollow microspheres were easily prepared by hydrothermal method. The scanning and transmission electron microscopy images demonstrated that the hybrid hollow microspheres possessed smooth outer shell and hollow interior. Their crystal structure, chemical state, amount of surface active groups and spectral response region were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, infrared spectra and UV-Vis diffuse reflection spectra, respectively. Methylene blue aqueous solution served as a target pollutant to evaluate the photo-catalytic activity under simulated sunlight. It turned out a higher photo-catalytic activity of boron doped hybrid hollow microspheres, comparing with the undoped ones.     

Si AMS measurement with ΔE-Q3D method

Accelerator mass spectrometry (AMS) is one of the most promising methods for the measurement of trace amount of ³²Si for its advantages of small sample size, short measurement time and extremely high sensitivity. However, the isobaric interference from ³²S often badly hinders the AMS measurement of ³²Si. The ΔE-Q3D detection technique established in this work brought about an overall suppression factor of larger than 10¹² for ³²S. As a result, a sensitivity of better than 1 × 10⁻¹⁴ (³²Si/Si) has been achieved, based on the measurement of a blank sample.