Particle manifold method (PMM): A new continuum‐discontinuum numerical model for geomechanics     

L. Sun  G.F. Zhao  J. Zhao 《国际地质力学数值与分析法杂志》2013,37(12):1711-1736

Particle manifold method (PMM) is a new extension of the numerical manifold method (NMM). PMM uses a mathematical cover system to describe the motion and deformation of a particle‐based physical domain. By introducing the concept of particle into NMM, PMM takes the advantages of easy topological and contact operations with particles. In this article, the methodology, formulations and implementation of the method are presented, together with modelling examples for validation. It is found that good solutions for both continuous and discontinuous problems are obtained by the new developed PMM. Due to the underlying coupled continuum‐discontinuum property of PMM, it has great potential for modelling of geomechanical problems. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

周期脉冲撞击的两分量Bose-Einstein凝聚系统的单粒子相干和对纠缠     

严冬  宋立军 《海洋学报》2010,32(10):6832-6836

在周期脉冲撞击的两分量Bose-Einstein凝聚系统中,研究了量子混沌对单粒子相干和对纠缠性质的影响.研究表明,混沌促使单粒子相干发生强烈衰减并保持着较低的相干度,同时对纠缠出现最大值并在较短时间后消失.利用单粒子相干的这种性质可以直接测量量子混沌存在的相空间结构,有利于预防Bose-Einstein凝聚的瓦解和控制凝聚体的混沌行为.  相似文献   

长春台磁暴特征研究     

岳庆祥 《东北地震研究》1993,(1)

依据长春地震台记录的磁暴资料,系统总结了第19、20、21三个太阳活动周磁暴特征,并对全球M_s≥7.8级地震的发生与太阳黑子活动、磁暴的关系进行了初步探讨。  相似文献   

The influence of aerosol particle composition on cloud droplet formation     

A. Hallberg  J. A. Ogren  K. J. Noone  K. Okada  J. Heintzenberg  I. B. Svenningsson 《Journal of Atmospheric Chemistry》1994,19(1-2):153-171

A difference in partitioning between cloud droplets and interstitial air for two chemical species (elemental carbon and sulphur) with different expected behaviour in nucleation scavenging was observed in clouds at Mt. Kleiner Feldberg (825 m asl), near Frankfurt, Germany. The fraction of sulphur incorporated in cloud droplets was always higher than the fraction of elemental carbon. This difference in partitioning has also been observed in fog but under different pollution conditions in the Po Valley, Italy. Both these studies were based on bulk samples. In the present study at Kleiner Feldberg, impactor samples of the particles in the interstitial air and the cloud droplet residuals were taken and a single particle analysis was done on the samples. It was found that, for a given particle size, the majority of particles forming cloud droplets were soluble and that insoluble particles preferentially remained in the interstitial air.  相似文献   

大气有机污染分析和评价I．采样方法及采样误差     

郎庆勇 《岩矿测试》1994,(3)

对近１０年来国外有关大气污染物的采样方法、有机污染物在气、固相中的分配以及采样误差的主要文献做了简要回顾。对不同采样器的采样效率、误差来源及误差校正方法进行了讨论。列举了一些富有指导意义的研究成果和结论。可以看出，在消除或限制了采样误差后，所得分析结果为客观评价环境污染问题提供了更可靠的依据。  相似文献   

准晶体的构筑原理及微粒分数维结构模型   总被引：7，自引：1，他引：7  

彭志忠 《地球科学》1985,(4)

准晶体的原子构造中两个原理在起作用,即二十面体原理和黄金中值原理。二十面体原理是指大小相近的原子形成孤立的十二次配位体时,二十面体配位形式在能量上最有利。黄金中值原理是指在准晶体中原子的排列符合黄金中值律。这两个原理适用于由少量原子构成的体系,也适用于某些生物的结构。运用这两个原理于准晶体微粒,我们获得了最简单的准晶体结构模型。此模型可以解释Al-Mn准晶体的高分辨图的所有细节。此模型与Hiraga模型以及Bursill和彭菊琳模型都不相同。在此模型中Al_(12)Mn二十面体不是共棱的。这一模型具有分数维结构的待征,因此称之为准晶体的微粒分数维结构模型。  相似文献   

Research Status and Progress of Balloon-borne Cloud and Precipitation Particles Probe     

Peng Wang  Lei Liu  Xichuan Liu  Shuai Hu  Shijun Zhao  Wenming Ji  Taichang Gao 《地球科学进展》1986,35(7):704-714

The accurate observation of the microphysical structure of cloud and precipitation plays an important role in understanding the formation of clouds and precipitation. In-situ measurement using measuring instruments carried by meteorological balloons is an effective way to obtain the microphysical properties of cloud and precipitation particles, which is a supplementary means for aircraft to observe cloud and precipitation particles. This observation method plays a more and more important role in in-situ measurement. According to the difference of the working principle of the existing balloon-borne cloud and precipitation particles probes, the detectors can be divided into particle impact-sampling sensors, particle imaging sensors, light-scattering sensors, light intensity attenuation sensors and charge measurement sensors. The working principles, key technologies and main advantages and disadvantages of typical instruments were summarized, and their applications to detailed cloud structure acquisition, cloud remote sensing method establishment, cloud and precipitation physical process research and parameterization, and scientific observation of thunderstorm clouds were briefly introduced. Finally, the development trend of balloon-borne cloud precipitation particle detectors was prospected, which will provide reference for related technical research and equipment development.  相似文献   

IAP AGCM中短波辐射方案的改进研究II·短波辐射方案的改进     

张凤  曾庆存 《气候与环境研究》2005,(3)

在Version 2的基础上,对短波辐射方案进行进一步的改进:引入了新增非灰体气体吸收效应、冰晶粒子形状效应和尺度效应以及云的不均匀性效应(称为Version 3)。数值模拟试验结果表明:Version 3能更好地模拟出全球冬、夏季的降水场、海平面气压场及地表气温场的主要分布特征,并且能相当准确地反映出这几个场的季节性变化特征。Version 3对这3个场的模拟能力明显优于原版本(Version 1)。此外,它对东亚地区的季风降雨具有很好的模拟能力,能较好地反映东亚区域降水的季节性变化。可见,Version 3为进一步研究云-辐射相互作用提供了很好的模式基础。本工作还清楚地表明,模式的进一步发展必须进行对相关物理过程中各个因子的更精确刻画,只有这样,模式才能得到更好的模拟能力。  相似文献   

NUMERICAL STUDY ON THE MIXING OF UNSORTED SEDIMENT PARTICLES DISCHARGED INTO A CROSS-FLOW BY MULTIPHASE PARTICLE-IN-CELL （MP-PIC） METHOD     

Jie GU Chiwai LI Hong YANG Yong ZHAN 《国际泥沙研究》2007,22(2):150-159

The mixing characteristics of dredged sediments of variable size discharged into cross-flow are studied by an Eulerian-Lagrangian method. A three-dimensional (3D) numerical model has been developed by using the modified k-ε parameterization for the turbulence in fluid phase/water and a Lagrangian method for the solid phase/sediments. In the model the wake turbulence induced by sediments has been included as additional source and sink terms in the k-ε model; and the trajectories of the sediments are tracked by the Lagrangian method in which the sediment drift velocities in cross-flow are computed by a multiphase particle-in-cell (MP-PIC) method and the diffusion process is approximated by a random walk model. The hydrodynamic behavior of dumped sediment cloud is governed by the total buoyancy on the cloud, the drag force on each particle and velocity of cross-flow. The cross-flow destroys more or less the double vortices occurred in stagnant ambience and dominates the longitudinal movement of sediment cloud. The computed results suggest satisfactory agreement by comparison with the experimental results of laboratory.  相似文献   

The fate of inorganic colloidal particles in Lake Brienz     

Vincent Chanudet  Montserrat Filella 《Aquatic Sciences - Research Across Boundaries》2007,69(2):199-211

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