基于MATLAB的CO2电流信号处理建模及仿真

CO2气体保护焊的短路过渡脉冲对电弧传感器信号处理存在较大的干扰.采用MATLAB的Simulink 建模仿真分析了传统的信号处理方法对其处理时存在的问题.提出了小波分析的电流信号软件处理方法,利用C 语言和MTALAB的M文件编写了电流信号小波分析的S函数模块,结合电弧传感器的分度脉冲信号进行动态仿真.结果表明,该方法很好地滤除短路尖峰脉冲,波形失真甚小.经试验验证,该方法正确可行,为电弧传感器信号提供了一种高精度的处理方法.     

基于声信号处理的窨井盖盗毁检测方法

为遏制偷盗和毁坏窨井盖行为,提出一种利用声信号对窨井盖偷盗和毁坏进行检测的方法。因不同声信号的能量基于频率的分布存在差异,将窨井盖产生的振动声信号进行FFT变换,将变换后的频谱转化为能量谱,利用统计方法确定窨井盖振动声信号能量在频率上的特征分布区间和分布阈值,计算其他干扰声信号的20个最大能量点在该特征区间的概率分布数并与阈值对比,判断窨井盖的振动声是否是遭受盗毁时敲击引起的。实验结果显示:窨井盖敲击声的能量分布与其他声信号具有明显不同,其能量分布的特征频率为48～504 Hz,分布阈值为85%。该方法能够有效识别盗毁窨井盖声音,且在一定信噪比环境下具有较强鲁棒性。     

基于Root MUSIC法的轧辊偏心参数估计

针对轧辊偏心信号是混杂在各种随机干扰中的复杂高频周期信号,因FFT法对信号分析的局限性,提出了一种Root MUSIC(Multiple Signal Classification)法和Prony法相结合的轧辊偏心信号估计新方法。利用Root MUSIC法准确估计出偏心谐波的频率及谐波的个数,同时使用Prony方法估计出偏心信号的各次谐波幅值和相位。仿真结果验证了可行性和有效性,在信噪比较低的情况下仍能准确地同时估计出偏心谐波的频率、幅值及相位,尤其在频率分辨率和抗噪声上比FFT法具有优越性     

陶瓷原材料市场绿色采购的信号传递博弈研究

陶瓷原材料市场由于信息不对称,容易造成绿色原材料供应商的逆向选择,导致陶瓷原材料绿色采购市场帕累托最优交易不能实现。从分析陶瓷原材料绿色采购逆向选择成因入手,通过建立绿色采购供需双方的信号传递博弈模型,具体分析了三种贝叶斯精炼均衡成立的条件,并且为供需双方行为提出建议,以便提高绿色采购市场交易效率。     

Regulation of protein tyrosine phosphatase 1C: opposing effects of the two src homology 2 domains

The regulatory roles of the two src homology 2 (SH2) domainsof protein tyrosine phosphatase 1C were investigated by comparingrecombinant full-length PTP1C with mutants in which either theN-terminal SH2 (N-SH2) domain (PTP1CANSH2), the C-terminal SH2(C-SH2) domain (PTP1CACSH2) or both SH2 domains were deleted(PTP1CANSH2ACSH2). This revealed that the SH2 domains have opposingand independent effects on activity: strong inhibition by N-SH2(42-fold) and weak activation by C-SH2 (2.1-fold). C-SH2 causedactivation across a wide pH range while N-SH2 inhibited mostat neutral and high pH through a shift of the basic limb ofthe pH profile of kmt/Km, apparently via perturbation of anactive-site pKa value. A phosphotyrosyl peptide derived fromthe erythro-poietin receptor caused an {small tilde}30-foldactivation of PTP1C and PTP1CACSH2 but had no effect on PTP1CANSH2or PTP1CANSH2ACSH2, indicating that binding of this peptideto N-SH2 abolished its inhibition. Since C-SH2 separates N-SH2from the catalytic domain in full-length PTP1C and activationis observed for PTP1CACSH2, it appears that the inhibitory effectof N-SH2 is independent of the position in the sequence andthat intermolecular interactions may also be possible     

熔滴过渡光谱信号模式识别分类器的设计

以熔化极气体保护焊电弧光谱信号作为样本,设计了一种熔滴过渡模式识别分类器.首先对光谱信号进行预处理并抽取了多个关键性的特征参数,通过降维分析得到一组新的特征向量.随后建立了相应的识别函数和最小距离法分类器.最后利用检验样本对分类器的性能进行了检验和评价.判别结果表明,利用该分类器能够较好地对MIG焊和C02焊熔滴过渡类型进行自动识别,具有较高的准确性和识别精度,为实现熔化极气体保护焊熔滴过渡自动控制奠定了基础.     

An approach based on current and sound signals for in-process tool wear monitoring

This paper presents a tool condition monitoring system (TCMS) for on-line tool wear monitoring in turning. The proposed TCMS was developed taking into account the necessary trade-off between cost and performance to be applicable in practice, in addition to a high success rate. The monitoring signals were the feed motor current and the sound signal. The former was used to estimate the feed cutting force using the least squares version of support vector machines (LS-SVM). Singular spectrum analysis (SSA) was used to extract information correlated with tool wear from the sound signal. The estimated feed cutting force and the SSA decomposition of the sound signal alone with the cutting conditions constitute the input data to the TCMS. Again LS-SVM was used to estimate tool condition and its reliability for on-line implementation was validated by experiments using AISI 1040 steel. The results showed that the proposed TCMS is fast and reliable for tool condition monitoring.     

电机电流分析法在机床类设备诊断中的应用研究

机床类设备传动链复杂,结构紧凑且封闭,对传动系统状态监测一直没有有效的分析办法,即使在噪声增大等恶劣情况下,常规的振动诊断方法也难以奏效.本文尝试用电流信号分析法,简称MCSA(Motor Current Signal Analysis),对机床状态进行测试和分析.通过电机电流信号的传动链齿轮谱特征分析,对其做出了正确评估,表明定子电流能很好地反映机床传动系统部件的运行状况.同时进行了多种运行工况的测试与试验,研究结论对机床类设备的生产制造和现场运行状态的分析提供了有效依据.     

基于DSP320F2812的数字化CO2焊机研制

设计了数字化CO2焊机的硬件结构,并根据CO2焊接工艺的特点,编写了相应的控制软件,实现了整个焊接系统的数字化.试验结果表明,基于DSP320F2812芯片控制的焊接电源具有良好的动特性,获得了较好的控制效果,为控制策略的智能化和最优化提供了良好的平台.     

CO2焊接电弧瞬态信号的检测、显示和分析

采用Visual C^ 开发了一套信号采集、信号处理、实时显示的焊接电信号测试分析软件。该软件具有界面友好，简单易用的特点，包含了统计、微分等多种模块。利用这些模块可对CO2气保焊的熔滴过渡电弧特性进行分析，从而提取有价值的焊接电弧特性信息。