并条12cm～14cm机械波的实例分析

分析并条波谱图12 cm～14 cm处机械波产生的原因。利用电容式条干均匀度仪检测纱条条干不匀,通过延长其测试时间,使检测波长达到或超过25个,以保证波谱图的可信度;同时根据不匀曲线图计算对应在并条波谱图上的机械波波长值,经分析及试验验证后认为:并条机一罗拉或传动一罗拉的齿轮或轴承出现了问题,都会造成并条12 cm～14 cm的机械波。     

空透机滑动轴承故障诊断

本文通过ＢＺ－８７０１袖珍式测振仪和ＦＦＴ动态分析仪配套，采集透平空压机滑动轴承的振动特征信号，用图表和谱图准确地判断出机组的故障部位及损坏程度。     

Computing Deblurred Time-Frequency Distributions Using Artificial Neural Networks

This paper presents an effective correlation vectored taxonomy algorithm to compute highly concentrated time-frequency distributions (TFDs) using localized neural networks (LNNs). Spectrograms and pre-processed Wigner–Ville distributions of known signals are vectorized and clustered as per the elbow criterion to constitute the training data for multiple artificial neural networks. The best trained networks become part of the LNNs. Test TFDs of unknown signals are then processed through the algorithm and presented to the LNNs. Experimental results demonstrate that appropriately vectored and clustered data once processed through the LNNs produce high resolution TFDs. Examples are presented to show the effectiveness of the proposed algorithm via analysis based on entropy and visual interpretation. This work was supported by the Higher Education Commission (HEC) of Pakistan under the 200 Merit Scholarship Scheme.     

逆合成孔径激光雷达鸟类目标成像方法研究

对鸟类目标进行高分辨成像是确保飞行安全的重要举措。针对现有雷达分辨率过低问题,提出了利用逆合成孔径激光雷达进行鸟类目标高分辨成像探测的构想。给出了逆合成孔径激光雷达实现鸟类成像的原理框图,以此为基础,建立了鸟类目标成像模型。仿真结果表明:本文模型可以获得鸟类目标高分辨像。     

具有大旋翼一类旋转部件的雷达目标成像

由于目标本身或目标部件的振动和旋转运动而引入的微多普勒谱会对目标主体的ISAR像造成污染,严重时无法对目标主体进行成像。介绍了雷达目标回波信号中的微多普勒信号产生原理,提出了一种微多普勒信息分离与提取的方法,基于旋转部件的微多普勒谱与目标主体谱在谱图域表现形式的不同,将旋转部件的微多普勒谱与目标主体谱分离后获得了具有大旋转部件一类目标的清晰像,同时也获得了目标旋转部件的一些运动及结构信息。最后,仿真结果验证了此方法的有效性。     

工程测量数据中的粗差诊断和处理技术

从测量数据序列的时-频特征出发,借助频谱图识别测量数据中的粗差的位置和性质。采用加权的均方误差准则来优化估计模型的参数,实现对测量序列的抗扰最佳估计。实例表明利用频谱图进行粗差诊断准确可靠,采用加权误差能量函数的小波神经网络估计模型具有逼近性能好、收敛速度快的优点,并能够有效地消除粗差对估计结果的影响。     

An automatic acoustic bat identification system based on the audible spectrum

Nowadays the task of monitoring bat species is a very difficult task because of several factors. The main ones are the difficulty of creating databases automatically and the particularities of the vocalizations of bats. For this reason, it is common to extract bat calls manually from a recording and treat them individually. We propose a new form of identification and labeling process based on adapting bat calls to the audible spectrum and significantly reducing the noise of its spectrogram. This process can be performed automatically from a recording made in a natural area. Our database consists of 189 h of recordings obtained in various natural areas in Costa Rica. 50 bats calls of 7 different classes are extracted from this database. We have obtained an average error of 2.7% and 3 of the 7 classes have an error below 1%.     

非对称离子迁移谱技术产品化过程中气路的设计

本文简单介绍了非对称离子迁移谱技术的发展，原理及应用。主要讲述了该技术在产品化过程中遇到的外载气流的不稳给样品峰带来的抖动这一问题，该问题对产品对非对称离子迁移谱技术在产品化过程中的可靠性及稳定性产生的非常重要的影响。本文通过蕈新设计气路连接方式，在气路上另外串接一小型流量控制器，有效的解决了外载气流不稳给气路带来的影响，并通过气路实验对这一结果进行了有效的验证。     

细纱前胶辊机械波的产生原因及预防措施

细纱前胶辊在纺纱运转中会产生8 cm～10 cm的机械波,介绍了胶辊机械波的波谱图特征,分析了胶辊机械波产生的主要原因,指出了在生产管理、胶辊制作、运转操作方面采取的预防措施.     

几种假机械波及不规则波谱图和曲线图的分析

为准确分析采用条干均匀度仪测试所得波谱图和曲线图,找出波谱图和曲线图中异常曲线的产生原因,结合多年对电子条干均匀度仪的应用实践,指出由于纺纱过程中纺纱捻度、张力的影响以及有关测试部件磨损和操作方法不当等,会产生各种假机械波、不规则波谱图及曲线图,并归纳了这类图形的形成特点及识别方法.实际分析时,一定要分清楚是真机械波还是假机械波.