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Time-averaged Behaviour at the Critical Parameter Point of Transition to Spatiotemporal Chaos

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Chinese Physics Letters 2001年第9期18卷 1176-1178页

作者： HE Kai-Fen The Key Laboratory of Beam Technology and Material Modification of Ministry of Education and Institute of Low Energy Nuclear PhysicsBeijing Normal UniversityBeijing 100875 Beijing Radiation Center Beijing 100875

A time-averaged behaviour is found to be important for investigating the critical behaviour in parameter space for the transition from temporal chaos to spatiotemporal chaos by using an energy representation. Considering any wave solution as a superposition of the steady wave with its perturbation wave, we find that when approaching the critical parameter point the averaged positive interaction energy for the k = 1 mode becomes competitive with the negative one, with the summation displaying a scaling behaviour of power law.

关键词： behaviour chaos averaged

Development of SOM combustion model for Reynolds-averaged and large-eddy simulation of turbulent combustion and its validation by DNS

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Science China(Technological Sciences) 2008年第8期51卷 1073-1086页

作者： ZHOU LiXing Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China Department of Engineering Mechanics Tsinghua University Beijing China

The derivation and closure methods of the second-order moment (SOM) combus- tion model are proposed. The application of this model to Reynolds averaged (RANS) and large-eddy simulation (LES) of turbulent swirling diffusion combustion, jet diffusion combustion, and bluff-body stabilized premixed combustion is sum- marized. It is indicated that the SOM model is much better than the eddy-beak-up (EBU) and presumed PDF models widely used in commercial software and engi- neering. The SOM modeling results are close to those obtained using the most accurate but much more complex PDF equation model. Moreover, it can save much more computation time than the PDF equation model. Finally, the SOM model is validated by the direct numerical simulation (DNS) of turbulent reacting channel flows.

关键词： turbulent combustion second-order moment model Reynolds averaged simulation large-eddy simulation

The Properties of Expected Scattering and averaged Scattering and Their Applications to Texture Classification

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Chinese Quarterly Journal of Mathematics 2019年第2期34卷 138-151页

作者： WANG Juan ZHAO Jie College of Science Zhongyuan University of Technology

In order to further improve the effectiveness of image processing,it is necessary that an efficient invariant representation is stable to deformation applied to *** motivates the study of image representations defining an Euclidean metric stable to these *** paper mainly focuses on two *** the one hand,in this paper,two properties of expected scattering and averaged scattering,i.e.,Lipschitz continuity and translation invariance,are proved in *** properties support that excepted scattering and averaged scattering are invariant,stable and informative *** the other hand,the issue of texture classification based on expected scattering and averaged scattering has been analyzed respectively in this *** features,which are based on expected scattering and averaged scattering,are calculated and used for *** results show that starting with the seventh feature,the two approaches can achieve good performance in texture image classification.

关键词： Translation invariance Lipschitz continuity Texture image classification Expected scattering averaged scattering

Solution structure of N-terminal segment of hepatitis B virus surface antigen Pre-S1

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Science China(Life Sciences) 1998年第5期41卷 530-541页

作者：龚庆国吴季辉刘琴施蕴渝崔大敷徐来根张友尚 Laboratory of Structural Biology University of Science and Technology of China Chinese Academy of Sciences China School of Life Science University of Science and Technology of China Hefei China Shanghai Institute of Biochemistry Chinese Academy of Sciences Shanghai China

A synthetic peptide, the N\|terminus of hepatitis B virus surface antigen Pre\|S1, was studied by two\| dimensional NMR techniques. A series of 1 H nuclear magnetic resonance experiments were used to complete the identification of spin systems and sequential assignments of this 28\|residue peptide. 157 distance constraints and 55 dihedral angle constraints were obtained. 20 structures with the lowest target function were selected by the distance geometry program DIANA. Energy minimization and the following 100 ps time\|averaged restrained molecular dynamics （TRMD） simulation in aqueous solution were performed for each conformer. After TRMD simulation, three locally convergent regions corresponding to residues 22\31, 36\40, 41\46 were found. The averaged pairwise root\|mean\|square deviation （RMSD） of backbone atoms for them were （1.71±0.49）?, （0.76±0.31）?, （1.05±0.52）?, respectively. Four reverse turns found in these regions, residues 22\25, 37\40, 41\44 and 43\46, correspond to several important antibody binding sites revealed in relevant immunological research.

关键词： NMR solution structure hepatitis B virus surface antigen Pre\|S1 distance geometry time averaged restraints molecular dynamics simulation.

TR PIV Experimental Investigation on Bypass Transition Induced by a Cylinder Wake

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Chinese Physics Letters 2011年第5期28卷 172-175页

作者： TANG Zhan-Qi JIANG Nan Department of Mechanics Tianjin UniversityTianjin 300072 Tianjin Key Laboratory of Modern Engineering Mechanics Tianjin UniversityTianjin 300372

The process of laminar to turbulent transition induced by a cylinder wake is studied by time-resolved(TR)particle image velocimetry(PIV)in a water *** combination of multi-scale local-averaged structure function analysis with criteria is used to identify the generation of secondary transverse vortex structure andto track its evolution along the *** the beginning of transition,with the decent of cylinder wake vortex,the secondary vortex structure is induced near the *** the secondary vortex moves dovnstream,it is induced to lift up by the wake vortex,meanwhile they are diffused and *** to the method of spatial conditional average,a low-speedhump is found in the near-wallregion along the bypass transition zone,accompanied by a low-speed region in the free stream occupied by the vake *** further downstream,the hump in the near-wall region becomes more and more *** the later stage of transition zone,hairpin vortex can be seen by conditional-averaged low-pass filtered *** hairpin head is almost vertical to the wall with an inclination angle of about 90°,which is attributed to the additional lift-up behavior induced by wake *** can be concluded that in the process of bypass transition,the wake vortex would not only induce the secondary vortex but also leaven its growth and evolution,resulting in the robust and rapidly growing hairpin vortex.

关键词： vortex cylinder averaged

Heavy Quarkonium Spectra in a Quark Potential Model

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Chinese Physics Letters 2001年第12期18卷 1558-1560页

作者： CHEN Hong ZHANG Jingg DONG Yu-Bing SHEN Peng-Nian Department of Physics Southwest China Normal UniversityChongqing 400715 Institute of High Energy Physics Chinese Academy of SciencesBeijing 100039

By solving the eigenvalue equation for the quark-antiquark potential which emerges from an effective dilatongluon coupling inspired by superstring theory, we obtain the spin-averaged energy levels of charmonium (cc) and bottonium (bb) and show that the masses of the cc and bb states are well in agreement with the available experimental data.

关键词： quark eigenvalue averaged

Time-Domain Frequency Correction Method for Averaging Low-Field NMR Signals Acquired in Urban Laboratory Environment

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Chinese Physics Letters 2012年第10期29卷 213-216页

作者： QIU Long-Qing LIU Chao DONG Hui XU Lu ZHANG Yi Hans-Joachim Krause XIE Xiao-Ming Andreas Offenhäusser State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information TechnologyShanghai 200050 Peter Grünberg Institute(PGI-8) Forschungszentrum JülichJülichD-52425Germany Joint Research Laboratory on Superconductivity and Bioelectronics Collaboration between CAS-Shanghai and Forschungszentrum JülichShanghai 200050 Graduate University of the Chinese Academy of Sciences Beijing 100049

Using a second-order helium-cooled superconducting quantum interference device gradiometer as the detector,ultra-low-field nuclear magnetic resonance(ULF-NMR)signals of protons are recorded in an urban environment without magnetic *** homogeneity and stability of the measurement field are *** signals of protons are studied at night and during working *** Larmor frequency variation caused by the fluctuation of the external magnetic field during daytime reaches around 5 Hz when performing multiple measurements for about 10 min,which seriously affects the results of *** order to improve the performance of the averaged data,we suggest the use of a data processor,*** so-called time-domain frequency correction(TFC).For a 50-times averaged signal spectrum,the signal-to-noise ratio is enhanced from 30 to 120 when applying TFC while preserving the NMR spectrum *** TFC is also applied successfully to the measurement data of the hetero-nuclear J-coupling in 2,2,2-trifluoroethanol.

关键词： NMR averaged spectrum

Numerical Investigation on Drag Reduction Effect by Mass Injection from Porous Boundary Wall

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Transactions of Nanjing University of Aeronautics and Astronautics 2015年第2期32卷 250-254页

作者：赵勇高云姜宗玉王天霖邹丽 Transportation Equipment and Ocean Engineering College Dalian Maritime University State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University State Key Laboratory of Oil and Gas Reservoir Geology and Exploration Southwest Petroleum University Wood Group Mustang School of Naval Architecture Dalian University of Technology

Interaction between the injected flow from the porous wall and the main flow can reduce drag *** phenomenon is significant to the flight vehicle *** intensive flux of injection enhances difficulty of numerical simulation and requires higher demands on the turbulence model.A turbulent boundary layer flow with mass injection through a porous wall governed by Reynolds averaged Navier-Stokers(RANS)equations is solved by using the Wilcox′s k-ωturbulence model and the obtained resistance coefficient agrees well with the experimental *** results with and without mass injection are compared with other conditions *** profile,turbulent kinetic energy and turbulent eddy viscosity are studied in these two *** confirm that the boundary layer is blowing up and the turbulence is better developed with the aid of mass injection,which may explain the drag reduction *** numerical simulation may deepen our comprehension on this complex flow.

关键词： mass injection boundary layer blowing up drag reduction turbulence model Reyndds averaged Navier-Stokers(RANS)

THE WESTERN BOUNDARY CURRENT OF THE PACIFIC AND ITS ROLE IN THE CLIMATE

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Chinese Journal of Oceanology and Limnology 1991年第1期9卷 1-14页

作者：胡敦欣崔茂常 Institute of Oceanology Acaderma SinicaQingdao266071

On the basis of the CTD data gathered by the-R / V Science I in each Oct. of 1986-1988 and the winter averaged temperature anomaly in southeast China, the interannual variability of the Western Boundary Current (WBC) is examined in terms of volume transport by inverse calculation and its role in the climate is studied by statistical *** estimated transport is 50,20, and 33 x 106 m3 / s for the Kuroshio and 24,34, and 36 x 106 m3 / s for the Mindanao Current (MC)in October of 1986,1987, and 1988, *** WBC is the biggest channel in the ocean for transporting heat poleward and plays an extremely important role in establishing and maintaining the global heat balance. Results showed that meridional heat transport by the Kuroshio northeast of Luzon apparently dominates coldness or warmness in winter in southeast *** phenomena observed in the western Pacific but not in the western Atlantic are the warm pool and the equatorward flowing MC which, together with the North Equatorial

关键词： winter interannual southeast Atlantic northward meridional northeast anomaly gathered averaged