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Effect of focused ultrasound stimulation at different ultrasonic power levels on the local field potential power spectrum

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Chinese Physics B 2015年第8期24卷 646-650页

作者：袁毅路承彪李小俚 Institute of Electrical Engineering Yanshan University State Key Laboratory of Cognitive Neuroscience and Learning & IDG/Mc Govern Institute for Brain Research Beijing Normal University Center for Collaboration and Innovation in Brain and Learning Sciences Beijing Normal University

Local field potential(LFP) signals of the rat hippocampus were recorded under noninvasive focused ultrasound stimulation(FUS) with different ultrasonic powers. The LFP mean absolute power was calculated with the Welch algorithm at the delta, theta, alpha, beta, and gamma frequency bands. The experimental results demonstrate that the LFP mean absolute power at different frequency bands increases as the ultrasound power increases.

关键词： focused ultrasound stimulation local field potential power spectrum

Universal form of the power spectrum of the aero-optical aberration caused by the supersonic turbulent boundary layer

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Chinese Physics B 2014年第10期23卷 118-123页

作者：高穹易仕和姜宗福 College of Photon–Electron Science and Engineering National University of Defense Technology College of Aerospace Science and Engineering National University of Defense Technology

Based on the measurement of one-dimensional （1D） optical path difference （OPD） of the supersonic turbulent bound- ary layer, an analytical form for the power spectrum of the two-dimensional （2D） OPD is obtained with its structure function and under the locally homogeneous isotropic assumption. The universality of this spectrum is argued, and its validity is checked by the comparison with experimental result. The potential applications of this model in theoretical and numerical studies are emphasized. Another contribution of this work is around the application of correlation function to analyzing the statistics of OPD. Based on our results and other results published elsewhere, we show that the OPD is often not stationary, and one should be cautious about using this tool.

关键词： aero-optics supersonic turbulent boundary layer optical path difference power spectrum

A New Exactly Solvable Inflation Model and its power spectrum

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Chinese Physics Letters 2003年第2期20卷 192-194页

作者：李新洲刘道军等 ShanghaiUnitedCenterforAstrophysics ShangHaiNormalUniversitySHanghai200234 InstituteforTheoreticalPhysics EastChinaUniversityofScienceandTechnologyshanghai200237

We present a new exactly solvable inflation model in which inflation can stop automatically, and in the approximately de Sitter limit, we give its power spectrum which can be tested in the future observations of cosmi... 详细信息

关键词： power spectrum

AUTOREGRESSIVE MODEL AND power spectrum CHARATERISTICS OF CURRENT SIGNAL IN HIGH FREQUENCY GROUP PULSE MICRO-ELECTROCHEMICAL MACHINING

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Chinese Journal of Mechanical Engineering 2006年第2期19卷 260-264页

作者： TANG Xinglun ZHANG Zhijing ZHOU Zhaoying YANG Xiaodong Department of Precision Instrument ＆ Mechanics Tsinghua UniversityBeijing 100084 China School of Mechanical ＆ Vehicle Engineering Beijing Institute of TechnologyBeijing 100084 China Equipment ＆ Energy Department Guizhou Branch of Aluminum Co. Ltd.Guiyang 550014 China

The identification of the inter-electrode gap size in the high frequency group pulse micro-electrochemical machining （HGPECM） is mainly discussed. The auto-regressive（AR） model of group pulse current flowing across the cathode and the anode are created under different situations with different processing parameters and inter-electrode gap size. The AR model based on the current signals indicates that the order of the AR model is obviously different relating to the different processing conditions and the inter-electrode gap size; Moreover, it is different about the stability of the dynamic system, i.e. the white noise response of the Green＇s function of the dynamic system is diverse. In addition, power spectrum method is used in the analysis of the dynamic time series about the current signals with different inter-electrode gap size, the results show that there exists a strongest power spectrum peak, characteristic power spectrum（CPS）, to the current signals related to the different inter-electrode gap size in the range of 0～5 kHz. Therefore, the CPS of current signals can implement the identification of the inter-electrode gap.

关键词： Electrochemical machining Inter-electrode gap Autoregressive(AR) model power spectrum

A Combined Numerical-Experimental Study on the Noise power spectrum Produced by an Electromagnetic Sensor for Slurry Flow

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Fluid Dynamics & Materials Processing 2021年第3期17卷 511-529页

作者： Song Gao Xin Jin Qiaohong Liu College of Agricultural Equipment Engineering Henan University of Science and TechnologyLuoyang471023China School of Medical Instruments Shanghai University of Medicine and Health SciencesShanghai201318China

The signals generated by electromagnetic flow sensors used for slurry fluids are often affected by noise interference produced by interaction with the slurry *** this study,the power spectrum characteristics of the signal are studied,and an attempt is made to determine the relationship between the characteristics of the related noise and the velocity and concentration of the slurry *** experiments are conducted and the related power spectrum curve is obtained processing the signal measured by the sensor with *** simulations are also carried out in the frame of an Eulerian approach in order get additional insights into the considered problem through comparison with the experimental *** following conclusions are drawn:(1)The intensity of noise is directly proportional to the number of solid particles colliding with the electrode of the electromagnetic flow sensor per unit time,and to the square of the average velocity of the flow layer near the pipe wall.(2)With an increase in the slurry noise intensity,the power spectrum curve shifts upward in the logarithmic coordinate system(and vice versa).

关键词： Electromagnetic flow sensor slurry noise power spectrum kinetic energy theorem

Output power spectrum of a single-mode laser driven by coloured pump and quantum noises with coloured correlation

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Chinese Physics B 2004年第10期13卷 1717-1721页

作者：韩立波曹力吴大进 StateKeyLaboratoryofLaserTechnology HuazhongUniversityofScienceandTechnologyWuhan430074China CCAST(WorldLaboratory) Beijing100080China

By using the linear approximation method, the output power spectrum is calculated for a single-mode laser driven by coloured pump and quantum noises with coloured correlation. We have observed that the configuration of the output power spectrum is complicated: that is, it can be of single peak, two peaks or three peaks. The configurations of the power spectrum can be transformed from one into another by changing the cross-correlation time, the cross-correlation coefficient between the two noises, and pump noise intensity.

关键词： linear approximation method power spectrum coloured correlation noises

Analysis and optimization of power spectrum on EBPSK modulation in throughput-efficient wireless system

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Journal of Southeast University(English Edition) 2008年第2期24卷 143-148页

作者：冯熳戚晨浩吴乐南东南大学信息科学与工程学院南京210096

In order to satisfy increasingly greater demand for the performance of communication systems, a throughput efficient wireless system based on the extended binary phase shift keying （EBPSK） modulation is presented. Simultaneously, corresponding analysis of power spectra is also given with a brief process. The optimal waveform is proposed without useful information loss, by removing linear spectra presenting periodic components. On this basis, the reasonable definition of bandwidth is discussed, which indicates that the EBPSK belongs to the category of the ultra narrow band （UNB） throughput-efficient communication. Meanwhile, the modulation parameters＇ effects on bandwidth, transmission rate and transmission performance are analyzed. Results illustrate the validity of theoretical analysis and spectrum optimization. Results also prove that this UNB system can obtain good bit error rate （BER） performance with high spectra efficiency.

关键词： extended binary phase shift keying power spectrum ultra narrow band spectra efficiency

BP-Neural-Network-Based Tool Wear Monitoring by Using Wav elet Decomposition of the power spectrum

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International Journal of Plant Engineering and Management 2004年第4期9卷 198-204页

作者： ZHENGJian-ming XIChang-qing LIYan XIAOJi-ming InstituteofMechanicalandPrecisionInstrumentEngineering Xi＇anUniversityofTechnologyXi＇an710048P.R.China InstituteofMechanicalandPrecisionInstrumentEngineering Xi＇anUniversityofTechnologyXi＇an710048P.R.China

In a drilling process, the power spectrum of the drilling force is related tothe tool wear and is widely applied in the monitoring of tool wear. But the feature extraction andidentification of the power spectrum have always been an unresolved difficult problem. This papersolves it through decomposition of the power spectrum in multilayers using wavelet transform andextraction of the low frequency decomposition coefficient as the envelope information of the powerspectrum. Intelligent identification of the tool wear status is achieved in the drilling processthrough fusing the wavelet decomposition coefficient of the power spectrum by using a BP (BackPropagation) neural network. The experimental results show that the features of the power spectrumcan be extracted efficiently through this method, and the trained neural networks show highidentification precision and the ability of extension.

关键词： tool wear monitoring power spectrum wavelet transform BP neural network

Evaluation of Surface Roughness of Aluminum Alloy in Burnishing Process Based on Chaos Theory

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Chinese Journal of Mechanical Engineering 2023年第1期36卷 90-103页

作者： Zhipeng Yuan Zhenyu Zhou Zhiguo Jiang Zeyu Zhao Cong Ding Zhongyu Piao College of Mechanical Engineering Zhejiang University of TechnologyHangzhou310012ZhejiangChina Key Laboratory of Special Purpose Equipment and Advanced Processing Technology Ministry of Education and Zhejiang ProvinceZhejiang University of TechnologyHangzhou310012China

Burnishing experiments with different burnishing parameters were performed on a computer numerical control milling machine to characterize the surface roughness of an aluminum alloy during *** chaos theory was employed to investigate the nonlinear features of the burnishing *** experimental results show that the power spectrum is broadband and continuous,and the Lyapunov exponentλis positive,proving that burnishing has chaotic *** chaotic characteristic parameter,the correlation dimension D,is sensitive to the time behavior of the system and is used to establish the corresponding relationship with the surface *** correlation dimension was the largest,when the surface roughness was the ***,when the correlation dimension curve decreases,the roughness curve *** correlation dimension and surface roughness exhibit opposite variation *** higher the correlation dimension,the lower the surface *** surface roughness of the aluminum alloy can be characterized online by calculating the correlation dimension during burnishing.

关键词： Aluminum alloy burnishing power spectrum Correlation dimension Lyapunov exponent Surface roughness