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spectral analysis and self-adjusting mechanism for oscillation phenomenon in hydrogen-oxygen continuously rotating detonation engine

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Chinese Journal of Aeronautics 2015年第3期28卷 669-675页

作者： Liu Yusi Wang Yuhui Li Yongsheng Li Yang Wang Jianping Center for Combustion and Propulsion College of Engineering Peking University Center for Applied Physics and Technology Peking University State Key Laboratory for Turbulence & Complex Systems Peking University

Abstract The continuously rotating detonation engine （CRDE） is a new concept of engines for air- craft and spacecraft. Quasi-stable continuously rotating detonation （CRD） can be observed in an annular combustion chamber, but the sustaining, stabilizing and adjusting mechanisms are not yet clear. To learn more deeply into the CRDE, experimental studies have been carried out to inves- tigate hydrogen-oxygen CRDE. Pressure histories are obtained during each shot, which show that stable CRD waves are generated in the combustor, when feeding pressures are higher than 0.5 MPa for fuel and oxidizer, respectively. Each shot can keep running as long as fresh gas feeding main- tains. Close-up of the pressure history shows the repeatability of pressure peaks and indicates the detonation velocity in hydrogen-oxygen CRD, which proves the success of forming a stable CRD in the annular chamber. Spectrum of the pressure history matches the close-up analysis and confirms the CRD. It also shows multi-wave phenomenon and affirms the fact that in this case a single detonation wave is rotating in the annulus. Moreover, oscillation phenomenon is found in pressure peaks and a self-adjusting mechanism is proposed to explain the phenomenon.

关键词： Continuously rotatingdetonation Detonation engines Hydrogen-oxygendetonation Self-adjusting mechanism spectral analysis

spectral analysis of the Light Flash Produced by a Natural Dolomite Plate Under Strong Shock

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Plasma Science and Technology 2015年第5期17卷 409-414页

作者：唐恩凌徐名扬张庆明施晓涵王猛王迪相升海夏瑾韩雅菲张立佼吴尽张爽袁健飞 School of Equipment Engineering Shenyang Ligong University State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology

In order to obtain the elemental compositions of the projectile and target materials during 2A12 aluminum projectile shot on a natural dolomite plate, three kinds of experiments have been conducted using a spectral acquirement system established on a two-stage light gas gun for impact velocities ranging from 2.20 km/s to 4.20 km/s, at the same projectile incidence angle of 30°. Experimental results show that the elemental compositions of the projectile and target materials in the strong shock experiments have a good agreement with the original elemental compositions of the projectile and target. In addition, the relations between spectral radiant intensity and elemental compositions of the projectile and target materials have been obtained for different impact velocities, in which the spectral radiant intensity of the main elements in the material increases with increasing impact velocity, and more elements appear with increasing impact velocity since more energy would result from a higher velocity impact.

关键词： strong shock light flash spectral analysis spectral radiant intensity

spectral analysis OF RANDOM WAVE UPLIFT FORCE ON A HORIZONTAL DECK

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Journal of Hydrodynamics 2011年第1期23卷 81-88页

作者： SUN Jia-wen SUN Zhao-chen LIANG Shu-xiu ZHENG Kun State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024China

This article presents a spectral analysis of wave uplift loads on a horizontal *** wave uplift force spectrum on the underside of the deck is *** is shown that the wave uplift force spectral density decreases with the increase of the relative clearance1/3Δh /*** influences of different incident wave parameters,including the relative wave height1/3H /d,the relativedeck width/sB L and the relative clearance1/3Δh /Hon the dimensionless zeroth spectral moment of the uplift forces *** is found that the zeroth spectral moment of the uplift forces increases with the increase of the relative wave height1/3H /d,and decreases with the increase of the relative clearance1/3Δh /H.A new dimensionless prediction model for the zerothspectral moment of wave uplift loads on the deck is proposed and the relationship between the wave uplift forces and the zerothspectral moment of the uplift force are obtained.

关键词： spectral analysis wave uplift force spectral moment

spectral analysis OF THE FIRST-ORDER HERMITE CUBIC SPLINE COLLOCATION DIFFERENTIATION MATRICES

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Journal of Computational Mathematics 2002年第5期20卷 551-560页

作者： Ji-ming Wu Long-jun Shen Inst Appl Phys & Computat Math Lab Computat Phys Beijing 100088 Peoples R China

Presents a study that determined a theoretical proof for the spectral analysis result of the first-order Hermite cubic spline collocation differentation matrices. Background on the Hermite cubic spline collocation method; Basis of the argumentation in the study regarding the condensation technique and the Hurwitz theorem; Numerical results.

关键词： spline collocation differentiation matrices spectral analysis

Application of Wavelet Algorithm to spectral analysis of Oceanic Waves and Offshore Structure Responses

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China Ocean Engineering 2009年第4期23卷 635-644页

作者：徐继文王言英 Department of Naval Architecture Dalian University of Technology

Fourier transform （FF） is a commonly used method in spectral analysis of ocean wave and offshore structure responses, but it is not suitable for records of short length. In this paper another method, wavelet transform （WT）, is applied to ＇analyze the data of short length. The Morlet wavelet is employed to calculate the spectra density functions for wave records and simulated Floating Production Storage and Offloading （FPSO） vessels＇ responses. Computed wave data include simulated wave data based on JONSWAP spectrum and the recorded data of Storm 149 from North Alwyn. Wavelet method is validated by comparing the statistical characteristics by WF method and those by fast Fourier transform （FFT） method with those of target spectra. The spectral density fnnctions＇ shapes calculated by WT are less malformed and have less error of statistical characteristics compared with those by FT especially when the record lengths decrease.

关键词： spectral analysis wavelet transform fast Fourier transform small sample simulation wave response

Pinning synchronization of networked multi-agent systems: spectral analysis

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Control Theory and Technology 2015年第1期13卷 45-54页

作者： Linying XIANG Fei CHEN Guanrong CHEN Department of Automation Xiamen University Department of Electronic Engineering City University of Hong Kong

Pinning synchronization of a networked multi-agent system with a directed communication topology is investigated from a spectral analysis approach. Some new types of synchronized regions for networked systems with different nonlinear agent dynamics and inner coupling structures are discovered. The eigenvalue distributions of the coupling and control matrices for different types of directed networks are obtained. The effects of the network topology, pinning density and pinning strength on the network synchronizability are examined through extensive numerical simulations. It is shown that the synchronizability of the pinned network can be effectively improved by increasing pinning density and pinning strength for some types of synchronized regions, whereas too large the pinning density and pinning strength will lead to desynchronization for other types. It is found that directed random networks are not always easier to synchronize than directed small-world networks, and a denser eigenvalue distribution may not always imply better synchronizability.

关键词： Multi-agent system directed network pinning control spectral analysis synchronizability synchronized region

Research　on　the　spectral　analysis　and　testmethod　of　period　signals　in　monthly　mean　sea　level

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Acta Oceanologica Sinica 1995年第2期14卷 181-190页

作者： Ma Jirui Tian Suzhen Zheng Wenzhen and Chai Xinmin (Institute of Marine Scientific and Technological Information, State Oceanic Administration, Tianjin 300171, China Research Institute of Marine Strategies, State Oceanic Administration, Beijing 100081, C

This paper summarizes the general methods,existing problems and their causes of the period analysis for the monthly mean sea level and points out that it is the key to the analysing period signals and forecasting the change trend of the monthly mean sea level that the periods of the signals are selected reasonably. As there are often many period signals in these series, nonlinear effects exist between pairs of period signals. In order to avoid the false periods that may be introduced due to the effects of side lobes and the periods with statistical phase significance coherence that may be introduced due to the effects of nonlinear effects and their restraint to other period signals, the maximum entropy spectral analysis and the corresponding significance period test may be performed repeatedly on the basis of the bispectrum analysis and meanwhile the most significant period component is filtered out by the least square filtering method, i. e., the method of the significance period analysis with mixed spectra modeled by a nonlinear system is adopted and the signal periods approaching the reality are selected one by one. The examples of the bispectrum analysis, the signal period analysis by mixed spectra and the fitting parameters for combined period components with linear trend in the time series of monthly mean sea level are given in this paper.

关键词： Monthly mean sea level nonlinear bispectrum spectral analysis period analysis linear trend

Influence of signal-to-noise ratio on accuracy of spectral analysis by near infrared spectroscopy

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Journal of Measurement Science and Instrumentation 2020年第3期11卷 211-216页

作者： ZHUANG Xin-gang SHI Xue-shun LIU Hong-bo LIU Chang-ming ZHANG Peng-ju WANG Heng-fei The 41st Research Institute of China Electronics Technology Group Corporation Qingdao 266555China National Opto-Electronic Primary Metrology Laboratory Qingdao 266555China Science and Technology on Electronic Test&Measurement Laboratory Qingdao 266555China

As one of the important indicators of spectrometer,signal-to-noise ratio(SNR)reflects the ability of spectrometer to detect weak *** investigate the influence of SNR on the prediction accuracy of spectral analysis,we first introduce the major factors affecting the spectral *** green tea as an example,the influence of spectral SNR on the prediction accuracy of the origin identification model is analyzed by *** the same time,the relationship between the spectral SNR and prediction accuracy of spectral analysis model is *** on this,the common methods for improving the spectral SNR are *** results show that the accuracy of the prediction set model first decreases slowly,then decreases linearly,and finally tends to be flat as the spectral SNR *** calculation,in order to achieve the prediction accuracy of prediction model reaching 90%and 85%,the spectral SNR is required to be higher than 23.42 dB and 21.16 dB,*** overall results provide certain parameters support for the development of new online analytical spectroscopic instruments,especially for the technical indicators of SNR.

关键词： near infrared spectroscopy signal-to-noise ratio(SNR) partial least squares(PLS) spectral analysis green tea

A NEW COMPUTING MULTIVARIATE spectral analysis METHOD BASED ON WAVELET TRANSFORM

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2000年第1期 18-22页

作者：程翼宇陈闽军

This paper proposes a new algorithm for multivariate calibration named Principal Component Regression Based on Wavelet (PCRW) which combines wavelet decomposition technique with the factor analysis method for establishing a duplicate denoising mechanism. A practical example in spectral analysis of a typical multicomponent pharmaceutical system was used to verify the effectiveness of the algorithm. It was shown that PCRW produced fewer prediction errors than those obtained by using PCR.

关键词： spectral analysis wavelet transform multivariate calibration chemometrics PCRW