Coal bump is a dynamic process,thus it is necessary to reveal the process validly.2D-ball code is an efficient approach developed by the authors based on the basicDEM rationale proposed by Cundall.Numerical simulation...Coal bump is a dynamic process,thus it is necessary to reveal the process validly.2D-ball code is an efficient approach developed by the authors based on the basicDEM rationale proposed by Cundall.Numerical simulations show that the coal bump experiencesa process of energy accumulation,sudden release of energy and energy decrease.The stiffness of coal particles has a great influence on the coal bump morphosisand particle velocity.Generally,the larger the stiffness of particles,the longer the shootingoff period and the larger the bump velocity.This is in agreement with the results of laboratoryexperiment and in-situ studies.However,the stiffness of particles has an influence onthe quantity value energy and no influence on the releasing energy pattern of the coalbump.展开更多
From the analysis and the contrast of band-limited ray tracing method based on Kirchhoff integral, it was found that the method performs many approximations in the derivation process and omits the derivative term of t...From the analysis and the contrast of band-limited ray tracing method based on Kirchhoff integral, it was found that the method performs many approximations in the derivation process and omits the derivative term of the phase factor in the Kirchhoff integral. Numerical calculations and analysis show that the omission of cor-relation terms in Kirchhoff integrals has a non-negligible effect on the calculation results, and the different terms in the Kirchhoff integral have different effects on different frequency ranges. The method can be applied to ve-locity models containing complex interfaces without changing waves and continuous media. the velocity model and can be extended to elastic waves and continuous media.展开更多
The Bingham fluid model has been successfully used in modeling a large class of non-Newtonian fluids. In this paper, the authors extend to the case of Bingham fluids the results previously obtained by Chipot and Marda...The Bingham fluid model has been successfully used in modeling a large class of non-Newtonian fluids. In this paper, the authors extend to the case of Bingham fluids the results previously obtained by Chipot and Mardare, who studied the asymptotics of the Stokes flow in a cylindrical domain that becomes unbounded in one direction, and prove the convergence of the solution to the Bingham problem in a finite periodic domain, to the solution of the Bingham problem in the infinite periodic domain, as the length of the finite domain goes to infinity. As a consequence of this convergence, the existence of a solution to a Bingham problem in the infinite periodic domain is obtained, and the uniqueness of the velocity field for this problem is also shown. Finally, they show that the error in approximating the velocity field in the infinite domain with the velocity in a periodic domain of length 2l has a polynomial decay in , unlike in the Stokes case （see [Chipot, M. and Mardare, S., Asymptotic behaviour of the Stokes problem in cylinders becoming unbounded in one direction, Journal de Mathgmatiques Pures et Appliqudes, 90（2）, 2008, 133-159]） where it has an exponential decay. This is in itself an important result for the numerical simulations of non-Newtonian flows in long tubes.展开更多
Using observations from the EUV Imaging Spectrometer （EIS） onboard Hinode, we exam the plasma dynamics around the edge of the active region 10977, possibly associated with the source of nascent slow/intermediate sol...Using observations from the EUV Imaging Spectrometer （EIS） onboard Hinode, we exam the plasma dynamics around the edge of the active region 10977, possibly associated with the source of nascent slow/intermediate solar wind. The correlation between the temporal profiles of the radiation intensity and Doppler shift for each emission line are analyzed. And three small regions with positive correlations for all the five emission lines are selected for a detailed analysis. In this work, Doppler blue （red） shift is defined as negative （positive）. We find that in Region 1, the radiation intensity （Doppler velocity） decreases by about 15% （about 3 km s-X）, and logarithmical differential emission measures （lg（DEMs）） reduces by about 0.06-0.10% at all temperatures, called ＂weak dimming＂, during a 30-min interval. In Region 2 and Region 3, however, the radiation intensity （Doppler velocity） increases by about 15% （about 3 km s-l）, and lg（DEMs） increases by about 0.06%~0.10% at all tempera- tures, called ＂weak brightening＂. Such weak dimming （weak brightening） could reflect a slow draining （replenishing） of plas- ma in the solar wind flux tubes, possibly due to a larger （smaller） outflow flux at high altitude than at low altitude. These sug- gest that the plasma supply could be intermittent with an alternation of draining and replenishing, for which the underlying physical process is yet unknown, at the source region of slow/intermediate solar wind.展开更多
基金Supported by the National Natural Science Fundation of China(50534080,50674063)Taishan Scholar Engineering Construction Fund of Shandong Province of China(J06N04)
文摘Coal bump is a dynamic process,thus it is necessary to reveal the process validly.2D-ball code is an efficient approach developed by the authors based on the basicDEM rationale proposed by Cundall.Numerical simulations show that the coal bump experiencesa process of energy accumulation,sudden release of energy and energy decrease.The stiffness of coal particles has a great influence on the coal bump morphosisand particle velocity.Generally,the larger the stiffness of particles,the longer the shootingoff period and the larger the bump velocity.This is in agreement with the results of laboratoryexperiment and in-situ studies.However,the stiffness of particles has an influence onthe quantity value energy and no influence on the releasing energy pattern of the coalbump.
基金Supported by National Natural Science Foundation of China(No.41274120)
文摘From the analysis and the contrast of band-limited ray tracing method based on Kirchhoff integral, it was found that the method performs many approximations in the derivation process and omits the derivative term of the phase factor in the Kirchhoff integral. Numerical calculations and analysis show that the omission of cor-relation terms in Kirchhoff integrals has a non-negligible effect on the calculation results, and the different terms in the Kirchhoff integral have different effects on different frequency ranges. The method can be applied to ve-locity models containing complex interfaces without changing waves and continuous media. the velocity model and can be extended to elastic waves and continuous media.
基金supported by the University of Rouen and the Fédération Normandie Mathématiques, respectively
文摘The Bingham fluid model has been successfully used in modeling a large class of non-Newtonian fluids. In this paper, the authors extend to the case of Bingham fluids the results previously obtained by Chipot and Mardare, who studied the asymptotics of the Stokes flow in a cylindrical domain that becomes unbounded in one direction, and prove the convergence of the solution to the Bingham problem in a finite periodic domain, to the solution of the Bingham problem in the infinite periodic domain, as the length of the finite domain goes to infinity. As a consequence of this convergence, the existence of a solution to a Bingham problem in the infinite periodic domain is obtained, and the uniqueness of the velocity field for this problem is also shown. Finally, they show that the error in approximating the velocity field in the infinite domain with the velocity in a periodic domain of length 2l has a polynomial decay in , unlike in the Stokes case （see [Chipot, M. and Mardare, S., Asymptotic behaviour of the Stokes problem in cylinders becoming unbounded in one direction, Journal de Mathgmatiques Pures et Appliqudes, 90（2）, 2008, 133-159]） where it has an exponential decay. This is in itself an important result for the numerical simulations of non-Newtonian flows in long tubes.
基金supported by the National Natural Science Foundation of China(Grant Nos.41174148,41222032,40931055,41231069,41274172)supported by a foundation for the Author of National Excellent Doctoral Dissertation of China(FANEDD)(Grant No.201128)
文摘Using observations from the EUV Imaging Spectrometer （EIS） onboard Hinode, we exam the plasma dynamics around the edge of the active region 10977, possibly associated with the source of nascent slow/intermediate solar wind. The correlation between the temporal profiles of the radiation intensity and Doppler shift for each emission line are analyzed. And three small regions with positive correlations for all the five emission lines are selected for a detailed analysis. In this work, Doppler blue （red） shift is defined as negative （positive）. We find that in Region 1, the radiation intensity （Doppler velocity） decreases by about 15% （about 3 km s-X）, and logarithmical differential emission measures （lg（DEMs）） reduces by about 0.06-0.10% at all temperatures, called ＂weak dimming＂, during a 30-min interval. In Region 2 and Region 3, however, the radiation intensity （Doppler velocity） increases by about 15% （about 3 km s-l）, and lg（DEMs） increases by about 0.06%~0.10% at all tempera- tures, called ＂weak brightening＂. Such weak dimming （weak brightening） could reflect a slow draining （replenishing） of plas- ma in the solar wind flux tubes, possibly due to a larger （smaller） outflow flux at high altitude than at low altitude. These sug- gest that the plasma supply could be intermittent with an alternation of draining and replenishing, for which the underlying physical process is yet unknown, at the source region of slow/intermediate solar wind.
