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621.
Debasish Roy Biswajit Sahu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(3):1039-1048
Within a quantum hydrodynamic model and using the reductive perturbation technique, the nonlinear ion-acoustic wave (IAW) excitations due to a moving charged object in an electron-pair-ion quantum plasma are studied both analytically and numerically. In such quantum plasmas we have derived forced Korteweg-de Vries (fKdV) type equation for finite amplitude nonlinear IAWs. The effect of relevant plasma parameters on solitonic excitations is investigated. Numerical simulation shows the generation of advancing solitons ahead of the forcing term traveling at a faster rate with trailing wakes behind the forcing disturbance. It is found that propagation characteristics of nonlinear excitations are significantly affected by quantum parameter. Additionally, we have pursued our analysis by extending it to account for arbitrary amplitude IA solitons, and derived a system of nonlinear differential equations which are analyzed numerically to study the dynamics. Nonlinear analysis predicts the existence of periodic and quasiperiodic nature of the nonlinear system and reveals that the transition from quasiperiodic to periodic behavior occurs due to the variation of quantum diffraction. 相似文献
622.
构建农村和谐社会的原则与模式 总被引:3,自引:0,他引:3
潘德冰 《郑州航空工业管理学院学报(管理科学版)》2007,25(3):93-99
从深层次(体制结构)上分析新中国成立以来我国农村不和谐的根本原因,提出构建农村和谐社会的原则及改革的创新思路:建立树-果结构体制下的大众股份制。并论述随着这一改革的成功,我国农村将变成一个经济、社会的运行、控制稳定有序,农村社会生产力高度发展,教育、卫生等各项事业蒸蒸日上,民主与法制显著改善(质的变化)的和谐社会。同时指明了:随着这一制度的确立,明晰了产权,奠定了农村综合改革的(舍社会主义市场经济的微观)基础,消除了“城乡分割的二元结构”及小农经济与市场经济的对立。 相似文献
623.
I.V. Chashei A.I. Efimov L.N. Samoznaev D. Plettemeier M.K. Bird 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,35(12):2195-2198
Measurements of the motion of plasma density inhomogeneities in the inner solar wind are presented. The speeds were estimated using a cross-correlation analysis of radio frequency fluctuations of the Galileo spacecraft measured simultaneously at widely spaced ground stations. The radial projections of the correlation baselines on the pattern plane were of the order of several thousand kilometers. For cross-correlation functions calculated with comparatively short averaging times, we find that a pronounced two-velocity configuration is occasionally observed over the range of heliocentric distances 20 R < R < 40 R. The typical mean speed for such observations is about 300–400 km/s and the difference between the two predominant speeds is about 150–200 km/s. These results may indicate that the density fluctuations are associated with slow magnetosonic waves propagating in opposite directions at the local speed of sound in the reference frame moving with the mean solar wind speed. Quite reasonable estimates of the solar wind speed and speed of sound are obtained from this model. Another possible explanation of the two-velocity structures is that two independent solar wind streams are present simultaneously along different segments of the radio ray path. 相似文献
624.
We briefly discuss the strong intermittent nature of the interplanetary magnetic field, observing that similarity between
its statistical properties and the passive scalar ones exists, and may arise from different dynamical mechanisms. 相似文献
625.
626.
数学均匀化方法(MHM)一般需要通过有限元方法(FEM)来实现,摄动阶次和单元阶次直接影响计算结果。在解耦格式中,各阶摄动位移是相应阶次的影响函数和均匀化位移导数的乘积。单元阶次的选取取决于影响函数和均匀化位移的精度要求,而摄动阶次的选取则主要依赖于虚拟载荷的性质和均匀化位移各阶导数的计算精度;针对周期性复合材料杆的静力学问题,在施加不同阶次的载荷时,通过选择合适阶次的单元和摄动阶次得到了精确解。使用类似的方法研究了2D周期性复合材料静力学问题,指出了四边固支作为周期性单胞边界条件以及宏观位移求导精度对计算结果将有很大的影响。强调了二阶摄动对数学均匀化方法计算精度的作用;在数值结果中,应用最小势能原理评估了各阶摄动数学均匀化方法的计算精度,数值比较结果验证了结论的正确性。 相似文献
627.
628.
629.
Recent developments of the physics of complexity in space plasmas are briefly reviewed. The definition of dynamical complexity
is provided. Concepts of probability distribution functions, wavelet transforms, intermittent turbulence, multifractal processes
and extreme events are described. Future directions for this emerging field are discussed. 相似文献
630.
This article investigates the near-field dynamics in a particle-laden round turbulent jet in a large-eddy simulation (LES). A point-force two-way coupling model is adopted in the simulation to reveal the particle modulation of turbulence. The particles mainly excite the initial instability of the jet and bring about the earlier breakup of vortex rings in the near-field. The flow fluctuating intensity either in the axial or in the radial directions is hence increased by particles. The article also describes the mean velocity modulated by particles. The changing statistical velocity induced by particle modulation implies the effects of modulation of the local flow structures. This study is expected to be useful to the control of two-phase turbulent jets. 相似文献