柴油机燃烧过程的分析诊断方法

提出了一种柴油机燃烧过程分析诊断方法——特征参数分析法 ,应用燃油有效热能率、滞燃期、预混合燃烧期、预混合燃烧率、预混合燃烧指数、扩散燃烧指数、燃烧效率等特征参数可对柴油机的燃烧过程进行系统的分析。应用该分析方法对复合增压柴油机的燃烧过程进行了分析 ,找到了一定的规律性。结果表明 ,应用特征参数分析方法可有效地分析柴油机的燃烧过程 ,为评价柴油机的工作过程提供了一种有用的分析诊断手段。

The modulation recognition based on decision-making mechanism and neural network integrated classifier

A neural network integrated classifier(NNIC) designed with a new modulation recognition algorithm based on the decision-making tree is proposed in this paper.Firstly,instantaneous parameters are extracted in the time domain by the coordinated rotation digital computer(CORDIC) algorithm based on the extended convergence domain and feature parameters of frequency spectrum and power spectrum are extracted by the time-frequency analysis method.All pattern identification parameters are calculated under the I/Q orthogonal two-channel structure,and constructed into the feature vector set.Next,the classifier is designed according to the modulation pattern and recognition performance of the feature parameter set,the optimum threshold is selected for each feature parameter based on the decision-making mechanism in a single classifier,multi-source information fusion and modulation recognition are realized based on feature parameter judge process in the NNIC.Simulation results show NNIC is competent for all modulation recognitions,8 kinds of digital modulated signals are effectively identified,which shows the recognition rate and anti-interference capability at low SNR are improved greatly,the overall recognition rate can reach 100%when SNR is12dB.

基于不同频率下疲劳裂纹扩展时声发射特性分析

为了探究Q345R材料在循环载荷作用下的性能,开展不同频率下疲劳裂纹扩展实验,对照疲劳载荷过程中的损伤过程,提取声发射信号特征参数并进行综合分析。研究发现不同加载频率下,材料疲劳裂纹扩展长度与循环次数的关系;同时通过声发射在线监测其过程中的特征参数,发现疲劳裂纹扩展和断裂过程中的规律性,为声发射技术应用于Q345R材料的在线检测提供了参考。