ACCUGRAM: A novel approach based on classification to frequency band selection for rotating machinery fault diagnosis

Frequency band selection (FBS) in rotating machinery fault diagnosis aims to recognize frequency band location including a fault transient out of a full band spectrum, and thus fault diagnosis can suppress noise influence from other frequency components. Impulsiveness and cyclostationarity have been recently recognized as two distinctive signatures of a transient. Thus, many studies have focused on developing quantification metrics of the two signatures and using them as indicators to guide FBS. However, most previous studies almost ignore another aspect of FBS, i.e. health reference, which significantly affect FBS performance. To address this issue, this paper investigates importance of a health reference and recognize it as the third critical aspect in FBS. With help of the health reference, the frequency band where the fault transient exists could be located. A novel approach based on classification is proposed to integrate all three aspects (impulsiveness, cyclostationarity, and health reference) for FBS. Classification accuracy is developed as a novel indicator to select the most sensitive frequency band for rotating machinery fault diagnosis. The proposed method (coined by accugram) has been validated on benchmark and experiment datasets. Comparison results show its effectiveness and robustness over conventional envelope analysis, the kurtogram, and the infogram.     

光照水电站装设筒形阀分析

筒形阀是一种新型的水轮机进水阀,它与球阀或蝴蝶阀相比较有防止机组飞逸事故扩大效果明显、减轻导叶全关时导水机构的快速破坏并减少漏水量,以及动水开启方便、所需时间短等优点,但对运行条件也有一定的要求。光照水电站是贵州省第1个拟采用筒形阀的电站,为此对装设筒形阀的可行性和必要性进行了认真的分析。     

随机减量技术中周期激励的影响及消除方法

本文针对机械系统中通常存在确定性周期激励的事实 ,论证了周期干扰成分的存在对提取的随机减量特征信号的影响 ,基于数字滤波技术提出了一种从周期干扰环境中提取随机减量特征信号的简便方法。在回转机械稳定性监测中的应用实例表明本文提出的方法是有效的。     

火炮身管内表面激光硬化处理的实验研究

提高身管寿命是火炮行业亟待解决的关键技术问题，激光表面改性技术是解决这一问题的有效方法之一。本文在分析激光表面相变硬化性能的基础上，对身管内表面进行了激光硬化处理实验研究，检测了其内表面阳线和阴线的硬化层硬度和深度，对比分析了离焦量和焦深对其内表面硬化层硬度的影响，并对激光相变硬化层金相组织进行了分析。经激光硬化处理后，身管的内表面硬度有明显提高，硬化层较深，且为很细的条状马氏体组织。     

An investigation into the effect of various chemical and physical treatments of a South African phosphogypsum to render it suitable as a set retarder for cement

The work describes various physical and chemical treatments to eliminate the deleterious effects of impurities in phosphogypsum on the delayed setting time and impaired strength development behaviour of cement to which it was added as a set regulator. The physical treatments included washing, milling, and ultrasonic treatment of the material, while the chemical treatments dealt with acidic and basic additions to the phosphogypsum during the washing stage. It was found that chemical treatment with a milk of lime solution, which is often recommended in literature, was ineffective in reducing set retardation. Treatment with ammonium hydroxide or sulphuric acid was more effective in this regard. Intergrinding phosphogypsum with slaked lime improved its effectiveness in reducing set retardation, but the use of unslaked lime was less effective and also resulted in marked reductions in compressive strengths. A combined treatment of wet milling phosphogypsum with a lime slurry in a ball mall was derived from these experiments and is recommended for full-scale plant applications.     

NaY晶化母液制备硅铝胶的技术探讨

在导向剂法合成Y型分子筛的工艺下，晶化母液中SiO₂的含量为50～55g/l,Na₂O含量为20～25g/l，相当于模数为1.65～2.58的稀水玻璃，将晶化母液分离处理后，在晶化母液中加入一定量的硫酸铝溶液使硅沉淀,经过滤和水洗后即可制备出合格的硅铝胶，以便进行重新利用。     

PTC热敏电阻的现状与发展趋势(续一)

基于对1995年以来,国内外PTC热敏电阻的研究,介绍了PTC热敏电阻用原料(BaCO3、TiO2、BaTiO3、SrCO3、PbO、Pb3O4、SrTiO3、PbTiO3、Y2O3、Nb2O5、CaCO3、SiO2等);材料(BaTiO3系、V2O3系及高分子);生产技术(瓷粉制造、烧成、芯片制造、质量评定、理化分析、片式PTC生产);重点产品(消磁、马达启动、限流及加热等用)以及基础研究(相变应力模型、表面势垒模型)等方面的现状及今后的发展趋势。     

KZON-50/120空分设备的安装调试及设计改造

在KZON-50/120空分设备的安装调试和试运行过程中,对其机械和电器部分进行了多处改造,克服了原设计中存在的不足之处。改造后,机械和电器性能更加趋于合理,操作简单,便于维护,降低了制气费用,提高了制气纯度和经济效益,保证了空分设备更加安全可靠运行。     

Method to Characterize the Air Flow and Water Removal Characteristics During Vacuum Dewatering. Part II—Analysis and Characterization

This is part II of a study reported earlier on a method to characterize the air flow and water removal characteristics during vacuum dewatering. This article presents experimental data and analysis of results from the use of a cyclically actuated vacuum dewatering device for removing moisture from wetted porous materials such as paper with the intermittent application of vacuum and accompanying air flow though the material. Results presented include sheet moisture content as a function of residence time and hence water removal rate under a variety of process conditions. Also, experimental results on air flow through the wet porous structure and hence the role and importance of air flow during vacuum dewatering are presented. Vacuum dewatering process conditions include exit solids content between 11 and 20% solid under applied vacuum conditions of 13.5 to 67.7 kPa (4 to 20 in. Hg). Regression analysis indicated that the exit sheet moisture content exhibited a nonlinear relationship with residence time with exit solids reaching a plateau after a certain residence time. Final moisture content correlated linearly with the average overall flow rate of air through the paper sample and the basis weight of the material.     

我国先进制造技术的现状和发展途径

介绍了现在制造业中面临的问题，通过对问题的分析，提出了发展先进制造前沿技术的见解和在我国发展先进制造技术的途径，同时展望了先进制造技术的发展前景。