状态诊断中的波形噪声处理

简述了估计发动机力矩信号的基本原理,针对估计过程中噪声对估计器的影响,通过在前馈网络引入一非线性噪声门限改善了效果,给出仿真结果。

正极性单点电晕放电可听噪声时域波形拟合及分析

基于实验室搭建的可听噪声时域测试平台,获得了正极性单点电晕放电产生可听噪声的时域波形。根据可听噪声时域波形的脉冲特性,提出了采用分段双指数函数来拟合单个可听噪声时域脉冲波形的经验波形,通过在时域和频域上对拟合结果和测量结果的对比研究,验证了所提出拟合波形的合理性。最后,基于长时间可听噪声时域测试结果分析了不同电压下分段双指数函数中的拟合参数和可听噪声波形参数的统计特性。实验结果表明,由于电晕放电的随机性,在同一电压下脉冲波形参数及波形拟合参数具有较大的波动性;可听噪声脉冲的时间间隔随着电压的增加有所降低,而脉冲宽度及视在持续时间在不同电压下变化不大。

BS EN 55035:2017中的高斯白噪声波形实现方法A Method to Generate Gaussian White Noise Waveform in BS EN 55035:201

针对BS EN 55035:2017第4.2.7节宽带脉冲传导骚扰测试中的高斯白噪声特殊波形要求,提出了基于matlab 滤波器构造函数产生高斯白噪声台阶,通过信号源的多载波合成功能对高斯白噪声台阶进行幅度调制,合成要求的高斯白噪声波形的方法。使用ARB toolbox composer调整高斯白噪声波形参数,可得到标准要求的周期脉冲信号。实测对比验证表明,高斯白噪声波形的实现方法正确。

Signal extraction for GPS deformation monitoring in mining survey

The basic signal model of deformation monitoring with GPS was introduced and the main problems of GPS deformation monitoring in mining area were discussed. For the problem of noise signal extraction in GPS deformation monitoring, the Kalman-EMD method was proposed to obtain the effective deformation signal. The reliability and effectiveness of the methodology were tested and verified by analog signal. The results of experiment in Mongolia show that the accuracy of the proposed GPS deformation monitoring model is equivalent to that of level method.

Characterization of pitting corrosion of 7A60 aluminum alloy by EN and EIS techniques

The pitting corrosion behaviors of 7A60 aluminum alloy in the retrogression and re-aging （RRA） temper were investigated by electrochemical impedance spectroscopy （EIS） and electrochemical noise （EN） techniques, and the microstructure and the second phase content of the alloy were observed and determined by scanning electron microscopy （SEM） and energy dispersive spectrometer （EDS）. The results show that there exist two different corrosion stages for 7A60 alloy in 3.5%NaCl solution, and the corrosion process can be detected by the appearance of EIS spectrum with two capacitive time constants and the wavelet fractal dimension D extracted from EN. SEM and EDS results also demonstrate that severe pitting corrosion in 7A60 alloy is mainly caused by electrochemical active MgZn2 particles, secondly by Al2MgCu and Mg2Si. Al7Cu2Fe particles make little contribution to the pitting corrosion of 7A60 alloy.

A Blind Adaptive Jamming Canceller Using Antenna Array for GPS Receiver

Traditional beamformers need to know the incident angle of the desired signal leading while its abili-ty to handle interference is limited.In this paper,the constrained steer vector of linearly constrained min-imum-variance(LCMV)beamformer is modified to make sidelobe null to direction of powerful jammer.Inaddition,the state-space concept is used to describe the anti-jammer filter,and Kalman filter algorithm isdeduced by building the observation model and measurement equation.The new method is more efficient oncomputation and more robust to survive environment with large scale variation in interference strength.Fi-nally,simulation results shows that the new approach can form the null with its depth in proportion to powerin direction of jammer,and has steady convergence process.The novel method can effectively improve thesignal-to-jammer-plus-noise power ratio(SJNR)of GPS signals to make the correlation peak easy to track.

Removal of noises from electromagnetic radiation of coal or rock with EEMD-adaptive morphological filter

The electromagnetic radiation （EMR） signal collected by monitoring system during coal or rock dynamic disaster may be interferred easily by electromagnetic noises in mines. The noises have a direct influence on the recognition and analysis of the EMR signal features during the disaster. With the aim of removing these noises, an ensemble empirical mode decomposition （EEMD） adaptive morphological filter was proposed. From the result of the simulation and the experiment, it is shown that the method can restrain the random noise and white Gaussian noise mixed with EMR signal effectively. The filter is highly useful for improving the robustness of the coal or rock dynamic disaster monitoring system.

Automated Recovery of the 2012 Sumatera Aftershock Sequence Using Waveform Cross Correlation

We assess the performance of waveform cross correlation as applied to automatic and interactive processing of the aftershock sequence of the April 11, 2012 Sumatera Ms（IDC） = 8.2 earthquake. The XSEL （cross correlation standard event list） is compared to the REB （Reviewed Event Bulletin） issued by the IDC （International Data Centre）. The latter includes 1,181 aftershocks between April 11 and May 25. To automatically recover the sequence, sixteen aftershocks were selected from the IDC SEL3 （Standard Event List） available on April 13 and used as master events. Waveform templates from only seven IMS （International Monitoring System） array stations with the largest SNR （signal-to-noise ratio） for the main shock were used to calculate cross correlation coefficients. Approximately 620,000 arrivals were detected and then used to build events according to the IDC definition. After conflict resolution between event hypotheses with similar arrivals found by more than one master, all survived hypotheses populated the XSEL. The total number of distinct hypotheses was 4,924, with 2,763 hypotheses not matched by the REB, i.e. potentially new REB events. To evaluate the quality of the XSEL, we randomly selected a representative portion （-15%） from 2,763 hypotheses and reviewed them interactively according to standard IDC rules and guidelines. There were 119 new REB events built and 145 XSEL hypotheses rejected. Several frequency and probability density distributions have been constructed for all detections, the associated detections, the XSEL detections, the detections in the new REB, and rejected events.

Security-Oriented Transmission Based on Cooperative Relays in Cognitive Radio

In this paper,we propose a securityoriented transmission scheme with the help of multiple relays in Cognitive Radio(CR).To maximise the Secrecy Capacity(SC)of the source-destination link in CR,both beamforming and cooperative jamming technologies are used to improve the performance of the Secondary User(SU)and protect the Primary User(PU).The effectiveness of the proposed scheme is demonstrated using extensive simulation.Both theoretical analyses and simulation results reveal that the proposed scheme contributes to the secure transmission of the SU with acceptable attenuation of the Signal-to-Noise Ratio(SNR)at the PU receiver,and the upper bound of the SC at the SU receiver is able to exploit the power allocation strategy.

面向智能化测定的心电监护仪波形特征多参数提取算法

为弥补医用心电监护系统的不足,实现对患者呼吸、血氧饱和度等体征信息的实时采集,设计面向智能化测定的心电监护仪波形特征多参数提取算法。通过研究心电信号产生机理的方式,确定监护仪波形的特征形式,再借助心电监护导联机制,完成面向智能化测定的心电信号特征分析。在此基础上,分析波形噪声的传输情况,并依照具体的R波峰参数值,建立实际提取度量条件,实现心电监护仪波形特征多参数提取算法的顺利应用。以呼吸、血氧饱和度两项数值作为监测指标设计仿真实验,结果表明与传统多参数遥测监护系统相比,多参数提取算法对于患者体征信息的采集实时性与准确性更强,能够较好弥补医用心电监护系统在实际应用方面的不足。