风力发电机组振动故障及信号分析技术综述

以双馈型风力发电机组为基础,从风力发电机组的分类与构成出发,介绍了风力发电机组的主要结构以及风能转化为电能的基本流程。同时以双馈型风力发电机组塔筒和机舱的振动、轴承的振动和齿轮箱的振动为重点,分析了双馈型风力发电机组的主要振动故障及特征。最后以包络谱分析技术为主,阐述了风力发电机组振动信号的分析处理技术的特点,并结合实例展现出其实际应用效果。     

A fractal approach for interpretation of local instantaneous temperature signals around a horizontal heat transfer tube in a bubbling fluidized bed

Temperature signals measured around a horizontal heat transfer tube in a bubbling fluidized bed have been analyzed using Hurst's rescaled range (R/S) analysis. This analysis estimates and identifies long-term persistence or correlation in measured time series. The Hurst exponent H, which is evaluated from R/S analysis, also provides the local fractal dimension of the time series. A new approach to analyze an air fluidized particle system is proposed based on the evaluation of the Hurst exponent. Two Hurst exponents can be evaluated from a single time series, one from the discrete time fractional noise (where the linearity of the signal is subtracted and short-term fluctuations are emphasized) and the other from the signal itself (without subtracting the linearity of the signal). The authors argue that the Hurst exponent obtained from discrete time fractional noise characterizes the particle motion, whereas the Hurst exponent obtained from the signal itself characterizes the bubble motion. Moreover, a comparison between these two Hurst components identifies the zones where an alternating type of contact between the tube surface and the bubble-emulsion phase occur. The results were interpreted in conjunction with the mutual information function. The mutual information function provides the relationship between the data points separated in time and uses only the statistical relationship between the data points. The mutual information functions and the Hurst exponents exhibited similar trends around the heat transfer tube.     

机载雷达显示终端中的视频处理

本文介绍新近研制的机载雷达光栅显示终端中的视频处理方法及其电路。在对视频信号进行显示格式处理的同时,利用少量附加电路,实现回波积累、滑窗检测和恒虚警处理。在多量程、多重复频率和多种扫描方式下,可由显示处理机8086对量化速率、积累次数及检测门限等参数按相应值编程。计算机仿真表明,该视频处理部件具有良好的性能。     

金属腐蚀染噪声发射信号的小波分析

利用小波变换的基本原理和方法,对Q235碳素结构钢的均匀点腐蚀染噪声发射信号进行分析。通过计算小波分解后各级频带能量占整个信号能量的百分比,确定出主能量频带后,去除非主能量频带的噪声信号,提取金属腐蚀声发射信号的典型特征。     

Mitochondrial Glycerol-3-Phosphate Acyltransferase-Dependent Phospholipid Synthesis Modulates Phospholipid Mass and IL-2 Production in Jurkat T Cells

Changes in glycerophospholipid metabolism with age and disease can have a profound effect on immune cell activation and effector function. We previously demonstrated that glycerol‐3‐phosphate acyltransferase‐1, the first and rate limiting step in de novo glycerophospholipid synthesis, plays a role in modulating murine T cell function. The resultant phenotype is characterized by decreased IL‐2 production, increased propensity toward apoptosis, and altered membrane glycerophospholipid mass similar to that of an aged T cell. Since T cells in previous experiments were harvested from GPAT‐1^?/? mice, questions remained as to what extent the macro environment of the model influenced the observed cellular phenotype. Therefore, we generated and phenotypically characterized a mitochondrial glycerol‐3‐phosphate acyltransferase (GPAM) deficient Jurkat T cell. Furthermore, this line was used to probe possible mechanisms by which GPAT‐1/GPAM regulates T cell function. We report here that many of the key dysfunctional characteristics of murine GPAT‐1^?/? T cells are recapitulated in the GPAMKD Jurkat T cell. We found striking decreased IL‐2 production along with altered phospholipid mass and increased incidence of apoptosis. Since PtdOH is an indirect downstream product of GPAM, we attempted to rescue IL‐2 production with PtdOH supplementation; however, this addition did not return IL‐2 production to normal levels. Interestingly, we did find significantly decreased Zap‐70 phosphorylation following stimulation, suggesting that GPAM deficiency may alter membrane based stimulatory signaling. These data show for the first time that GPAM deficiency results in an inherent defect in Jurkat T cell function and glycerophospholipid composition and that this defect cannot be rescued by addition of exogenous PtdOH.     

趋肤效应在过套管电阻率测井中的影响分析

过套管电阻率测井是通过测量金属套管上的微小电位差来计算地层视电阻率,本文分析了金属套管的趋肤效应现象,提出过套管测井激励信号源为超低频,过套管电阻率测井技术直接测量信号量级为微伏级,有用信号的量级为纳伏级。本文还分析了信号频率对检测的影响因素,并给出具体的解决方法。该结论用于指导过套管激励信号源以及弱信号检测系统的设计。     

求连续搅拌釜式反应器控制系统数学模型的计算机程序

信号流图是一种表示复杂控制系统中各变量间关系的很好的方法。利用 MASON 增益公式可以求得信号流图中输入变量与输出变量间的关系—即输入节点到输出节点的总传输。本文通过连续搅拌釜式反应器控制系统来探讨在计算机上实现 MASON 增益公式的方法,利用这种方法编制的 FORTRAN 程序可以用来求解信号流图两点间的总传输或数学关系式。程序在HP-1000机上调试通过。     

地震信号去卷的一种自适应滤波方法

本文讨论地震信号去卷问题,提出了一种新的自适应递推去卷滤波器,它由参数和信号估计的两段Bootstrap算法组成.其优点是:1)同增广状态Kalman滤波[2,3]相比,显著地减小了计算量;2)采用了虚拟噪声补偿技术,有效地克服了滤波的发散.仿真例子说明了方法有效性.     

Monitoring of tool fracture in milling

For untended manufacturing operations, in-process monitoring of tool fracture plays a critically important role. A tool fracture feature in the spectrum of the displacement signal of the spindle in milling has been discovered. Therefore, a new signal processing algorithm called the band-limited average energy method using the tool fracture feature to monitor tool fracture is proposed. The energy content of the tool fracture feature is extracted and normalised to detect tool fracture. It is shown, by theoretical studies and experimental results, that tool fracture can be detected under varying cutting conditions in milling.