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Investigation of stimulated Raman scattering in longitudinal magnetized plasma by theory and kinetic simulation

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Plasma Science and Technology 2021年第11期23卷 26-34页

作者： Hongyu ZHOU Yan YIN Kaiqiang PAN Chengzhuo XIAO Jinlong JIAO Duan XIE Tongpu YU Fuqiu SHAO Hongbin ZHUO Department of Physics National University of Defense TechnologyChangsha 410073People's Republic of China Laser Fusion Research Center China Academy of Engineering PhysicsMianyang 621900People's Republic of China Key Laboratory for Micro-/Nano-Optoelectronic Devices of Ministry of Education&Hunan Province Key Laboratory of Low-Dimensional Structured Physics and Devices School of Physics and ElectronicsHunan UniversityChangsha 410082People's Republic of China Collaborative Innovation Center of IFSA(CICIFSA) Shanghai Jiao Tong UniversityShanghai 200240People’s Republic of China School of Physics Peking UniversityBeijing 100871People’s Republic of China School of Electronic Information and Electrical Engineering Changsha UniversityChangsha 410003People’s Republic of China Center for Advanced Material Diagnostic Technology Shenzhen Technology UniversityShenzhen 518118People’s Republic of China

Stimulated Raman scattering(SRS)in a longitudinal magnetized plasma is studied by theoretical analysis and kinetic *** linear growth rate derived via one-dimensional fluid theory shows the dependence on the plasma density,electron temperature,and magnetic field ***-dimensional particle-in-cell simulations are carried out to examine the kinetic evolution of SRS under low magnetic intensity of w_c/w_0spectrum present quite different *** a relatively low-density plasma(ne~0.20 nc),the plasma wave presents typical absolute growth and the magnetic field alleviates linear *** in the plasma whose density is near the cut-off point(ne~0.23 nc),the magnetic field induces a spectral splitting of the backscattering and forward-scattering *** has been observed in simulations and verified by theoretical *** to this effect,the onset of reflectivity delays,and the plasma waves form high-frequency oscillation and periodic envelope *** split wavenumber Dk/k0 is proportional to the magnetic field intensity and plasma *** studies provide novel insight into the kinetic behavior of SRS in magnetized plasmas.

关键词： laser plasma interaction stimulated Raman scattering longitudinal magnetized plasma spectrum analysis electron plasma wave

Fractional Envelope analysis for Rolling Element Bearing Weak Fault Feature Extraction

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IEEE/CAA Journal of Automatica Sinica 2017年第2期4卷 353-360页

作者： Jianhong Wang Liyan Qiao Yongqiang Ye YangQuan Chen School of Science Nantong University School of Engineering University of California IEEE College of Automation Engineering Nanjing University of Aeronautics and Astronautics

The bearing weak fault feature extraction is crucial to mechanical fault diagnosis and machine condition monitoring. Envelope analysis based on Hilbert transform has been widely used in bearing fault feature extraction. A generalization of the Hilbert transform, the fractional Hilbert transform is defined in the frequency domain, it is based upon the modification of spatial filter with a fractional parameter, and it can be used to construct a new kind of fractional analytic signal. By performing spectrum analysis on the fractional envelope signal, the fractional envelope spectrum can be obtained. When weak faults occur in a bearing, some of the characteristic frequencies will clearly appear in the fractional envelope spectrum. These characteristic frequencies can be used for bearing weak fault feature extraction. The effectiveness of the proposed method is verified through simulation signal and experiment data. © 2017 Chinese Association of Automation.

关键词： Bearings (machine parts) Condition monitoring Extraction Fault detection Feature extraction Frequency domain analysis Hilbert spaces Mathematical transformations spectrum analysis

Study of the spectrum effect on the threshold of resonant magnetic perturbation penetration on J-TEXT

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Plasma Science and Technology 2022年第12期24卷 16-25页

作者： Feiyue MAO Nengchao WANG Zhuo HUANG Zhengkang REN Song ZHOU Chengshuo SHEN Xiaoyi ZHANG Ying HE Qi ZHANG Ruo JIA Chuanxu ZHAO Yangbo LI Bo HU Da Li Abba Alhaji BALA Zhipeng CHEN Zhongyong CHEN Zhoujun YANG Yunfeng LIANG Yonghua DING Yuan PAN the J-TEXT Team International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People's Republic of China College of Computer Science South-Central Minzu UniversityWuhan 430074People's Republic of China Physics Department Federal University DutseDutse 720101JigawaNigeria Forschungszentrum Jülich GmbH Institut für Energie-und Klimaforschung-PlasmaphysikPartner of the Trilateral Euregio Cluster(TEC)Jülich 52425Germany Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People's Republic of China

The spectrum effect on the penetration of resonant magnetic perturbation(RMP) is studied with upgraded in-vessel RMP coils on *** poloidal spectrum of the RMP field,especially the amplitudes of 2/1 and 3/1 components,can be varied by the phase difference between the upper and lower coil rows,ΔΦ=Φ_(top)-Φ_(bottom),where Φ_(top)and Φ_(bottom)are the toroidal phases of the n=1 field of each coil *** type of RMP penetration is found to be related to ΔΦ,including the RMP penetration of either 2/1 or 3/1 RMP and the successive penetrations of 3/1 RMP followed by the 2/1 *** cases with penetration of only one RMP component,the penetration thresholds measured by the corresponding resonant component are close for variousΔΦ.However,the 2/1 RMP penetration threshold is significantly reduced if the 3/1 locked island is formed in *** changes in the rotation profile due to 3/1 locked island formation could partially contribute to the reduction of the 2/1 thresholds.

关键词： tokamak error field resonant magnetic perturbation mode penetration spectrum analysis

Correlation analysis between the occurrence of epidemic in ancient China and solar activity

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Science China Earth Sciences 2023年第1期66卷 161-168页

作者： Si CHEN Yong WEI Xin’an YUE Kaihua XU Mingkun LI Wei LIN Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Beijing Institute of Genomics Chinese Academy of Sciencesand China National Center for BioinformationBeijing 100101China Center for Excellence in Animal Evolution and Genetics Chinese Academy of SciencesKunming 650223China

As the globe has witnessed the pandemic,epidemic diseases exert a strong impact on human beings and *** the Sun is the primary energy source of the Earth,some scientific pioneers attempted to search for the discernible relation between solar activity and the incidence of *** this study,the periodic changes and trends of ancient Chinese epidemic data were analyzed in comparison with those of sunspot numbers,a solar activity *** results show that the epidemic and solar activity changes are in good agreement to a certain extent,especially during the Gleissberg and the de Vries *** wavelet coherence shows that the frequency of the epidemic data and sunspot numbers are highly *** addition,results from the ensemble empirical mode decomposition illustrate consistent variations in low-frequency *** study has important implications for further understanding of the potential impact of solar activity on Earth’s biosphere,the underlying mechanism of which needs further exploration.

关键词： Epidemic Ancient China Solar activity spectrum analysis

Effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump

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Journal of Hydrodynamics 2020年第4期32卷 758-770页

作者： Ning Zhang Bo Gao Bin Xia Qi-feng Jiang School of Energy and Power Engineering Jiangsu UniversityZhenjiang 212013China School of Mechanical Technology Wuxi Institute of TechnologyWuxi 214121China Key Laboratory of Fluid and Power Machinery Ministry of EducationXihua UniversityChengdu 610039China

The volute tongue,as the crucial component inducing rotor-stator interaction,is detrimental to unsteady pressure pulsations of centrifugal *** the present paper,to investigate the effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump,three volute tongues are obtained through twice cuts,named cases 1,2,*** measuring points are evenly mounted on periphery of the volute casing to obtain unsteady pressure signals using high response *** amplitudes at the blade passing frequency fBPF and root mean square(rms)values in 0 Hz-500 Hz frequency band are applied to evaluate the cutting *** show that pressure spectrum is significantly affected by the volute tongue cut,especially for the component at *** different measuring points,influences of the volute tongue cut on three cases are not *** nns values,it is evident that cutting the volute tongue will lead to pressure energy increasing for most of the concerned measuring points,especially for the points at the far away region from the volute ***,from comparison with the original shape case 1,the averaged increment of the twenty points is more than 20%.So it is concluded that for this type centrifugal pump,cutting the volute tongue is not reasonable considering low pressure pulsation requirement.

关键词： Centrifugal pump volute tongue cut pressure pulsation spectrum analysis

TiO_2-assisted photo-catalysis degradation process of dye chemicals

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Journal of Environmental Sciences 2001年第1期13卷 64-68页

作者： LI Fang\|bai 1,2 , GU Guo\|bang\+2, HUANG Guo\|feng\+1, GU Yun\|li\+2, WAN Hong\|fu\+1 (1.Guangdong Institute of Eco\|Environment and Soil Science,Guangzhou 510650, China. E\|mail: fbli@*** 2.College of Chemical Engineering, South Technolog Guangdong Institute of Eco-Environment and Soil Science Guangzhou 510650 China. E-mail:[email protected] College of Chemical Engineering South Technology University Guangzhou510642 China

The photo-catalytic degradation pathway and degradation products of methylene blue, rhodamine B, methyl orange, and malachite green in aqueous TiO2 suspension irradiated by high pressure mercury lamp by means of UV-visible absorption spectra and ion chromatography were investigated. The photo-catalysis degradation of dye solutions with charges was greatly effected by pH value owing to the electrostatic model. The photo-degradation rate of dyes anion increased with the decrease of pH value, in contrast, the photo-degradation rate of dyes cation increased with the increase of pH value. And the absorption peaks diminished with a blue shift. After illuminated for 30 minutes, a part of dye chemicals were completely mineralized and transferred into inorganic species including chloride ion, ammonium ion, nitrate ion, sulfate ion. And the addition of 100 mmol/L H2O2 promoted the formation of inorganic species. In this study, the quantity of ammonium ion was much more than that of nitrate ion. That indicated the formation of nitrate is from ammonium. The purification rate of COD in four kinds of dye solution was 71.7%-88.7%. The decrease of COD of dyes solution implies the feasibility of the environmental application of photo-catalyzed process.

关键词： Chromatography Irradiation Mercury vapor lamps pH effects Photocatalysis spectrum analysis Titanium oxides

Design of multi-spectrum BRDF measurement system

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Chinese Optics Letters 2007年第3期5卷 168-171页

作者：赵忠义齐超戴景民 Department of Automatic Measurement and Control Harbin Institute of Technology

A multi-spectrum bidirectional reflectance distribution function （BRDF） measurement system was developed with the adoption of single reference standard measurement method. An arm-adjustable corner device was designed for the BRDF system. Changing the distance to the sample by moving the detector arm made the device applicable to different wavelengths. The system could be used for the spectrum range from visible light （0.6328μm） to mid-far infrared （10.6μm）, the facular size between 0.8 3 cm. The rotating limit of detector arm was ±180°, the rotation range of sample holding table was 360°, and the angle resolution was 0.036°. A silicon carbide sample was measured using this system with reflectance zenith from -55° to ＋55°. According to the error analysis, the measurement uncertainty of this device was about 6.42%.

关键词： Error analysis Optical variables measurement Silicon carbide spectrum analysis

Time-division multiplexing holographic display using angular-spectrum layer-oriented method(Invited Paper)

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Chinese Optics Letters 2016年第1期14卷 16-20页

作者：赵燕曹良才张浩谭巍吴圣函王崝杨强金国藩 State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision Instruments Tsinghua University

A time-division multiplexing method for computer-generated holograms （CGHs） is proposed to solve the problem of the limited space-bandwidth product. A three-dimensional （3-D） scene is divided into multiple layers at different depths. The CGH corresponding to each layer is calculated by an angular-spectrum algorithm that is effective at a wide range of propagation distances. All of the CGHs are combined into several group-CGHs. These group-CGHs are sequentially uploaded onto one spatial light modulator at a high frame rate. The spacebandwidth product can be benefited by the time-division processing of the CGHs. The proposed method provides a new approach to achieve high quality 3-D display with a fast and accurate CGH computation.

关键词： Bandwidth Holograms Holographic displays Light modulators Multiplexing spectrum analysis Time division multiplexing

A new approach to detecting weak signal in strong noise based on chaos system control

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Chinese Physics B 2010年第3期19卷 202-206页

作者：徐艳春杨春玲瞿晓东 Harbin Institute of Technology Heilongjiang University

In this paper, a chaos system and proportional differential control are both used to detect the frequency of an unknown signal. In traditional methods the useful signal is obtained through the Duffing equation or other chaotic oscillators. But these methods are too complex because of using a lot of chaos oscillators. In this paper a new method is presented that uses the Rossler equation and proportional differential control to detect a weak signal frequency. Substituting the detected signal frequency into the RSssler equation leads the Rossler phase state to be considerably changed. The chaos state can be controlled through the proportional differential method. Through its phase diagram and spectrum analysis, the unknown frequency is obtained. The simulation results verify that the presented method is feasible and that the detection accuracy is higher than those of other methods.

关键词： chaos system proportional differential control spectrum analysis signal detection