共查询到19条相似文献,搜索用时 859 毫秒
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为了准确检测出合金类构件内部存在的缺陷,本文针对镁合金构件的近中心缺陷和近表面缺陷,分别采用探头垂直入射和偏心入射的超声检测方式,然后运用自适应滤波去噪信号处理方法对原始信号及特征回波信号进行去噪处理。 相似文献
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介绍了化学机械抛光(CMP)中表面膜层为金属和非金属晶圆的在线终点检测原理.研究了窗口检测算法,实时检测光强变化趋势,抓取趋势特征点,从控制抛光过程,实现CMP在线终点检测.实验结果表明,检测算法可达到预期的检测精度,能够满足生产实际需要. 相似文献
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非高斯非平稳噪声的干扰问题在通信过程中是经常出现的。在非高斯非平稳背景噪声下,以前经常使用经典信号检测理论对信号进行检测,很难取得较为理想的效果。基于小波变换以及小波去噪原理,提出一种新的阈值处理方法,该方法能有效地去除噪声,使有用信号能从非高斯非平稳噪声中检测出来。实验结果表明,新方法不但去噪效果明显,而且获得了较高的分辨率和信噪比,检测性能较为理想,是对信号检测理论的一种有效推广。 相似文献
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光学发射光谱(OES)诊断技术是高密度等离子体刻蚀工艺过程的关键技术,OES信号作为一种实时信号可以用来预测刻蚀过程的进展程度和判断刻蚀性能的好坏.在自行研发的等离子体刻蚀机平台上,采用美国海洋公司的OES传感器系统,采集多晶硅刻蚀工艺中所产生的OES信号,利用主元素分析法(PCA)对OES数据进行压缩处理,提高了实时信号的快速处理能力.对实验数据的分析表明:波长为405 mn的OES谱线可以明确显示出等离子体刻蚀进程,是一条表征等离子体刻蚀过程的状态检测及终点检测控制的特征谱线.在此基础之上,提出了基于PCA法的终点检测算法,用以判断刻蚀终点. 相似文献
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一种改善微弱信号信噪比的小波变换消噪法 总被引:3,自引:0,他引:3
通过分析小波变换处理信号噪声的方法及其在微弱信号检测方面的不够完善之处,提出适合于极低信噪比条件下小波消噪法的信号检测原理和方法,即通过构造具有可调功能的阈值函数以及对小波分解系数处理方式的优化设计等方法,在强背景噪声中提取出微弱的信号特征信息,从而实现微弱信号的检测.最后通过Matlab仿真验证该方法的实验效果,理论和实验结果均表明此方法能较大幅度地改善信号比.这里阈值构造过程中充分考虑到了信噪比因素的影响,并对小波分解系数的处理也进行了合理优化,从而使得去噪效果有较大的改善. 相似文献
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油液金属磨粒检测传感器通过监测机械设备油路中的金属磨粒,可实时反馈机械设备故障特征。为了提升油液磨粒检测传感器的检测精度,文章提出一种针对油液磨粒信号的变分模态分解(Variational Mode Decomposition,VMD)结合小波分析的去噪方法。首先,通过计算各模态分量与原始油液磨粒信号的相关系数确定最优K值;其次,对原始信号进行VMD分解,筛选出特征分量;最后,利用小波阈值去噪方法对特征分量进行降噪处理。实验结果表明,与经验模态分解(Empirical Mode Decomposition,EMD)和传统小波去噪方法相比,本方法的信噪比最高,均方根误差最小,能量占比最大,在油液磨粒信号降噪效果中表现最好,有利于提升磨粒检测传感器的检测精度。 相似文献
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为了提高语音识别系统中语音端点检测的准确性,提出一种改进的多特征值语音端点检测方法.新方法首先对信号进行小波分解及小波去噪处理,对去噪后小波子带系数进行短时能量与基音周期两特征值的提取,综合考虑两特征值的大小来进行语音端点检测.实验证明,改进的检测方法提高了端点检测的抗噪性及准确度. 相似文献
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A signal processing method for the friction-based endpoint detection system of a chemical mechanical polishing(CMP) process is presented.The signal process method uses the wavelet threshold denoising method to reduce the noise contained in the measured original signal,extracts the Kalman filter innovation from the denoised signal as the feature signal,and judges the CMP endpoint based on the feature of the Kalman filter innovation sequence during the CMP process.Applying the signal processing method,the ... 相似文献
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A model for calculating friction torque during the chemical mechanical polishing(CMP) process is presented,and the friction force and torque detection experiments during the CMP process are carried out to verify the model.The results show that the model can well describe the feature of friction torque during CMP processing. The research results provide a theoretical foundation for the CMP endpoint detection method based on the change of the torque of the polishing head rotational spindle. 相似文献
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Endpoint detection method for CMP of copper 总被引:2,自引:0,他引:2
A novel method to detect the endpoint during Cu-CMP has been developed. It is based on the determination of the Cu concentration within the slurry on the pad that has just polished the wafer. The measurement of the ion concentration is performed using a capillary and an ion-selective electrode. The endpoint of the CMP process is detected by the decrease of Cu ion concentration, which is displayed by an decreased potential at the electrode. An experimental set-up has been established which can be applied to a commercial polishing tool. The method has been tested under various process conditions. The new endpoint detection system revealed to work independently of the polishing tool and the wafer size. 相似文献
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Chemical-mechanical planarization (CMP) has emerged as the most preferred method to achieve excellent global and local planarity
in the damascene-Cu process. As the feature sizes shrink, understanding the fundamentals of CMP is critical for successful
implementation of the CMP process in sub 0.35-μm technology. It is also important to understand the effects of mechanical
and tribological properties of the interlayer films on the CMP process to conduct successful evaluation and implementation
of these materials. In this paper, we present the mechanical and tribological properties of various interlayer films (SiO2, SiC, low-k B, low-k C, Ta, and Cu) and discuss the CMP process of the films in an alumina-based Cu slurry. Mechanical properties
were evaluated using a nanoindentation technique. A micro-CMP tester was used to study the fundamental aspects of the CMP
process. The coefficient of friction (COF) was measured during the process and was found to decrease both with downward pressure
and with platen rotation. An acoustic sensor, attached to the substrate carrier, was used to monitor the process, and the
signal was recorded to examine the difference in polishing behavior of these films. The acoustic emission (AE) signal was
found to increase with the increase in platen velocity and pressure. Effects of machine parameters on the polishing behavior
of the interlayer films and the correlation of mechanical properties with tribological properties have been discussed. 相似文献
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The problem of EEG evoked potential (EP) estimation is basically one of estimating a transient signal embedded in nonstationary mostly additive noise; and as such it is well suited to a nonstationary estimation approach utilizing, for example, the Kalman filter. The method presented in this paper is based on a model of the EEG response which is assumed to be the sum of the EP and independent correlated Gaussian noise representing the spontaneous EEG activity. The EP is assumed to vary in both shape and latency; the latter is assumed to be governed by some unspecified probability density; and no assumption on stationarity is needed for the noise. With the model described in state-space form, a Kalman filter is constructed, and the variance of the innovation process is derived; a maximum likelihood solution to the EP estimation problem is then obtained via this innovation process. The method was tested on simulated as well as real EEG data. 相似文献
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对金属零件激光成形过程闭环控制系统中,熔覆宽度的检测技术进行了研究,提出了一种基于卡尔曼滤波技术的熔覆宽度检测方法。利用视觉传感系统获取激光加工过程中的熔池图像,经过图像处理与图像标定求熔覆宽度作为参量建立系统状态方程和测量方程,应用卡尔曼滤波算法对图像上的熔宽和熔宽变化进行状态估计,得到最小均方差条件下的熔覆宽度最佳预测值,从而减小过程噪声和测量噪声引起的熔覆宽度测量偏差,测量平均误差由0.028 mm降为0.009 3 mm,实现加工过程熔覆宽度的精确检测。实验结果证明:将卡尔曼滤波技术应用到熔覆宽度检测过程中可以大大提高熔宽检测精度。 相似文献