检索结果-南通市图书馆

Reduction of ultrasonic echo noise based on improved wavelet threshold de-noising algorithm for friction welding

China Welding 2010年第3期19卷 61-65页

作者：尹欣张臻王旻 Department of Mechanical and Electrical Engineering Zhengzhou Institute of Aeronautical Industry Management Zhengzhou450015. Zhengzhou Institute of Aeronautical Industry Management Zhengzhou 450015. Henan No. 2 Thermal Power Construction Company Zhengzhou 450005.

In the ultrasonic detection of defects in friction welded joints, it is difficult to exactly detect some weak bonding defects because of the noise pollution. This paper proposed an improved threshold function based on the multi-resolution analysis wavelet threshold de-noising method which was put forward by Donoho and Johnstone, and applied this method in the de-noising of the defective signals. This threshold function overcomes the discontinuous shortcoming of the hard-threshold function and the disadvantage of soft threshold function which causes an invariable deviation between the estimated wavelet coeffwients and the decomposed wavelet coefficients. The improved threshold function is of simple expression and convenient for calculation. The actual test results of defect noise signal show that this improved method can get less mean square error （ MSE ） and higher signal-to-noise ratio of reconstructed signals than those calculated from hard threshold and soft threshold methods. The improved threshold function has excellent de-noising effect.

关键词： wavelet threshold friction welding de-noising improved algorithm

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

EMD-based Adaptive wavelet threshold for Pulse Wave Denoising

引用

Chinese Journal of Biomedical Engineering(English Edition) 2015年第1期24卷 1-8页

作者： XU Li-shengl SHEN Yan-hua ZHONG Yue KANG Yan Max Q.-H.Meng Sino -Dutch Biomedical and Information Engineering School Northeastern University Key Laboratory of Medical Image Computing (Northeastern University) Ministry of Education Department of Electronic Engineering The Chinese University of Hong Kong

It is inevitable that noises will be introduced during the acquisition of pulse wave signal, which can result in morphology changes of the original pulse wave,and affect the hemodynamic analysis and diagnosis based on pulse wave signals. In order to remove these noises, an adaptive de-noising method based on empirical mode decomposition(EMD) and wavelet threshold is proposed in this paper. Compared with the wavelet threshold method for denoising pulse wave, the proposed approach is more effective, especially at low signal-to-noise ratio.

关键词： pulse wave de-noising EMD adaptive filter wavelet threshold

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Research on Moving Target Detection Algorithm Based on MRA and wavelet threshold

Research on Moving Target Detection Algorithm Based on MRA a...

引用

第26届中国控制与决策会议

作者： Jingjing Wang Xiaodong Wang Jiande Wu Yugang Fan Guoyong Huang Faculty of Information Engineering and Automation Kunming University of Science and Technology Engineering Research Center for Mineral Pipeline Transportation of Yunnan

ISBN: (纸本)9781479937097

Aiming at solving the noise problem which had lowered the accuracy in the target detection result from the process of image-collection and image-transmission, the paper proposes a new target detection algorithm based on the improved wavelet threshold. Firstly, these images are filtered by a denoising method, which combines the wavelet threshold method with the correlation of the wavelet coefficients, and its "Zoom" feature can eliminate the negative impact of noise;then a combined algorithm which connects background subtraction and two consecutive inter-frame subtraction is set up in order to combine their advantages and improve the effect of target detection. Compared simulation results of the four models, the results show that the target detection method based on multi-scale wavelet threshold is reasonable and effective, and more suitable for the real-time target detection.

关键词： MRA wavelet threshold background subtraction inter-frame difference method moving target detection

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Study on the Image De-noising Algorithm of Adaptive threshold based on wavelet Transform in the Unclear Radiation Environment

Study on the Image De-noising Algorithm of Adaptive Threshol...

引用

第24届中国控制与决策会议

作者： Mao-song Lin, Gang Xie School of Information Engineering, Southwest University of Science and Technology, Mianyang, 621010

In order to get a better image in the nuclear radiation environment, this paper presents an adaptive threshold image de-nosing algorithm based on the concept of wavelet multi-resolution. First of all, remove the big isolated points by median filtering in the image;achieve the multi-resolution analysis by lifting wavelet transform;then obtain the threshold value of the wavelet coefficients by the Bayesian Shrink adaptive algorithm;finally recover the image by the inverse lifting wavelet transform. As a result of multi-resolution adaptive threshold method, the non-stationary characteristics of the signal can be described quite well, and remove the noise according to the distribution of the signal and noise at different resolutions. The experimental results show that this method can get a better de-nosing effect in the nuclear radiation environment.

关键词： median filtering wavelet de-nosing lifting wavelet transform wavelet threshold

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Study of Denoising in the Electricity Anti-Stealing Detection Based on VMD-WTD Combination

引用

Energy Engineering 2022年第4期119卷 1453-1466页

作者： Huakun Que Guolong Lin Wenchong Guo Xiaofeng Feng Zetao Jiang Yunfei Cao Jinmin Fan Zhixian Ni Metrology Center of Guangdong Power Grid Corporation Shenzhen518049China School of Automation Guangdong University of TechnologyGuangzhou510006China China-EU School of Clean and Renewable Energy Huazhong University of Science and TechnologyWuhan430074China

In order to solve the failure of electricity anti-stealing detection device triggered by the noise mixed in high-frequency electricity stealing signals,a denoising method based on variational mode decomposition(VMD)and wavelet threshold denoising(WTD)was applied to extract the effective high-frequency electricity stealing ***,the signal polluted by noise was pre-decomposed using the VMD algorithm,the instantaneous frequency means of each pre-decomposed components was analyzed,so as to determine the optimal K *** optimal K value was used to decompose the polluted signal into K intrinsic mode components,and the sensitive mode components were determined through the cross-correlation ***,each sensitive mode was ***,the reconstructed signal denoised using the wavelet threshold to obtain the denoised *** simulation analysis and experimental results show that the proposed method is superior to the traditional VMD method,FFT method and EMD method,as it can effectively eliminate the noise and enhance the reliability of high-frequency electricity stealing signal detection.

关键词： Electricity stealing electromagnetic interference variable mode wavelet threshold instantaneous frequency mean

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Developing an Innovative High-precision Approach to Predict Medium-term and Long-term Satellite Clock Bias

引用

Journal of Geodesy and Geoinformation Science 2023年第1期6卷 47-58页

作者： Xu WANG Hongzhou CHAI School of Resources and Civil Engineering Liaoning Institute of Science and TechnologyBenxi117004China Institute of Geospatial Information Information Engineering UniversityZhengzhou 450001China

A new prediction method based on the nonlinear autoregressive model is proposed to improve the accuracy of medium-term and long-term predictions of Satellite Clock Bias(SCB).Forecast experiments for three time periods were implemented based on the precision SCB published on the International GNSS Server(IGS)*** results show that the medium-term and long-term prediction accuracy of the proposed approach is significantly better compared to other traditional models,with the training time being much shorter than the wavelet neural network model.

关键词： Satellite Clock Bias(SCB) Median Absolute Deviation(MAD) wavelet threshold nonlinear autoregressive model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Single Trial Detection of Visual Evoked Potential by Using EMD and wavelet Filtering Method

引用

Chinese Journal of Biomedical Engineering(English Edition) 2011年第3期20卷 115-118,124页

作者： HE Ke-ren ZOU Ling TAO Cai-lin MA Zheng-hua ZHOU Tian-tong School of Information Science ＆ Engineering Changzhou University Changzhou 213164 China State Key Laboratory of Robotics and System （HIT） Harbin Institute of Technoilogy Harbin 150001 China

Empirical mode decomposition(EMD) is a new signal decomposition method, which could decompose the non-stationary signal into several single-component intrinsic mode functions (IMFs) and each IMF has some physical meanings. This paper studies the single trial extraction of visual evoked potential by combining EMD and wavelet threshold filter. Experimental results showed that the EMD based method can separate the noise out of the event related potentials (ERPs) and effectively extract the weak ERPs in strong background noise, which manifested as the waveform characteristics and root mean square error (RMSE).

关键词： EMD wavelet threshold ERP single trial extraction

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Fault Diagnosis of Rolling Bearing Based on WT-VMD and Random Forest

Fault Diagnosis of Rolling Bearing Based on WT-VMD and Rando...

引用

第32届中国控制与决策会议

作者： Hana Zhu Xueying Li Huiming Liu College of Automation and Electronic Engineering Qingdao University of Science and Technology

This paper presents a fault diagnosis method based on wavelet threshold（WT）,variational mode decomposition（VMD） and random ***,wavelet threshold method is used to preprocess the original vibration signal to reduce noise interference and enhance fault features;then VMD is used to decompose the denoised signal into several intrinsic mode functions（IMFs） and extract the center frequencies of each IMF;finally,these center frequencies will be input into the random forest classifier as feature vectors for fault type *** with the results of some existing fault diagnosis methods（such as EMD + variable prediction model,VMD + PSO-PNN,VMD + multi-scale permutation entropy + SVM）,it is found that this method greatly improves the accuracy of fault *** research results show that this method can effectively identify various fault types of rolling bearing.

关键词： wavelet threshold Variational Mode Decomposition Random Forest Rolling Bearing Fault Diagnosis

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：