共查询到20条相似文献,搜索用时 93 毫秒
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导出了有心力场中质点无量纲形式的轨道微分方程,给出了极角与极径之间的积分关系式,求出了n=2、n=-1和n=3时,在圆形轨道运动质点受到径向速度扰动后的轨道方程,提出了圆形轨道稳定性条件的图像分析方法. 相似文献
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采用不同的方法,对Breit-Pauli哈密顿中的自旋-其它轨道相互作用和轨道-轨道相互作用的球张量形式重新进行了推导,给出了自旋-其它轨道相互作用和轨道-轨道相互作用哈密顿的球张量形式的正确表达式,指出了文献中所列出的这类表达式的错误,提供了导出这些表达式的中间步骤. 相似文献
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本文研究在水平旋转的国台上滚动的球的动力学问题.推出在圆台匀速旋转和匀加速旋转两种情况下球相对于惯性空间的速度公式、角速度公式及摩擦力公式.当圆台匀速旋转时,球将做匀速圆周运动,甚至在原地自旋.当圆台做匀加速旋转时,球的轨道一般不是圆,只有在特定的初始条件下,球才可能继续绕圆台中心轴作匀加速圆周运动.球运动的这些动力学现象与带电粒子在圆形电磁场中的运动,二者之间存在着十分有趣的──对应关系.利用这些对应关系,使我们有可能用类比的方法,去想象并理解那些不易接受的概念. 相似文献
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用含有非球对称修正的FPLMTO和LDA+UDFT,LDA+USIC研究了NiO的电子结构,发现由于非球对称势场的引入,导致了占据的3d轨道eg分量的轨道有序化.结果表明在这一类复杂的强关联电子中,原子球内非球对称性多极势场对电子结构的影响已经比较明显:除了上述的轨道有序化以外,eg分量的位置下移,宽度明显变窄,呈现局域化的趋势;两种不同LDA+U方法计算得出的电荷转移能隙分别为337eV(DFT)和25eV(SIC).同时发现在NiO中,上、下Hubbard带实际上是由占据的和非占据的3deg轨道构成,3dt2g轨道和O2p轨道的杂化带具有较大的带宽,因而也具有一定的巡游特性.结果表明在NiO中有特征明显的3d电子轨道有序化.通过研究得出结论:在NiO这一类体系的电子结构计算中,势场的非球对称性部分和球间区势场的作用,以及轨道极化等因素都应该恰当地处理
关键词:
关联电子系统
过渡金属氧化物
电子结构 相似文献
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We theoretically investigate the motion of a ball rolling down on a periodical staircase. Our research is restricted in the case of completely inelastic collision when the ball falls down on the surface of the stairs. The ball is accelerated when it rolls cross the edge of the stair, while it is decelerated when it rolls on the horizontal surface due to the rolling friction. The competition between them causes two different regimes according to the parameters of the system. One is the steady moving regime in which the ball keeps moving forever, and the other is the still regime in which the ball finally stops after rolling on a finite number of stairs. The diagram of these two regimes is given in the reduced parameter space. The tendency that smaller scale of the staircase can keep moving on smaller inclined angle is found. 相似文献
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We summarize in this article an extensive experimental and theoretical effort carried out to understand the behavior of a single ball when rolling down a bumpy surface. This may appear to be a simple problem but in fact is one that displays a rich variety of different behaviors which allow us to understand better dissipative systems such as granular media. Studies performed previously have shown that the motion of the single ball on the rough surface can be characterized by three different dynamic regimes according to the different values of the two control parameters, the inclination angle theta and the ratio Phi=R/r, where R is the radius of the rolling ball and r the radius of the glass beads which make up the rough surface. The three regimes are a decelerated regime A, a stationary regime B, characterized by a constant average velocity and a jumping regime C. This result was found to be independent of the composition of the rolling ball and the rough surface. It has been demonstrated that regime B is characterized by a viscous-like friction force that appears for specific parameter values. This friction force can be explained by a model whose central ingredient is the geometry of the surface. The trajectory of the ball in regime B can be pictured as a driven random walk motion where the fluctuations of the local velocities are due to collisions of the moving sphere and the surface grains. A detailed analysis of diffusive properties of the motion is discussed. (c) 1999 American Institute of Physics. 相似文献
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The stability of the rolling motion of near space hypersonic vehicles with rudder control is studied using method of qualitative analysis of nonlinear differential equations, and the stability criteria of the deflected rolling motions are improved. The outcomes can serve as the basis for further study regarding the influence of pitching and lateral motion on the stability of rolling motion. To validate the theoretical results, numerical simulations were done for the rolling motion of two hypersonic vehicles with typical configurations. Also, wind tunnel experiments for four aircraft models with typical configurations have been done. The results show that: 1) there exist two dynamic patterns of the rolling motion under statically stable condition. The first one is point attractor, for which the motion of aircraft returns to the original state. The second is periodic attractor, for which the aircraft rolls periodically. 2) Under statically unstable condition, there exist three dynamic patterns of rolling motion, namely, the point attractor, periodic attractor around deflected state of rolling motion, and double periodic attractors or chaotic attractors. 相似文献
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A. P. Ivanov 《Doklady Physics》2016,61(6):285-287
The problem on the motion of a homogeneous ball on a horizontal plane is considered. The existence of the vector first integral independent of the friction character and the motion of the support plane in the horizontal directions is shown. In particular, the velocities of the ball center are identical at the moments of rolling on a motionless plane, which corresponds to experiments with the ANAIS billiard table. 相似文献
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We study the rolling motion of a small solid sphere on a fibrillated rubber substrate in an external field in the presence
of a Gaussian noise. From the nature of the drift and the evolution of the displacement fluctuation of the ball, it is evident
that the rolling is controlled by a complex non-linear friction at a low velocity and a low noise strength (K), but by a linear kinematic friction at a high velocity and a high noise strength. This transition from a non-linear to a
linear friction control of motion can be discerned from another experiment in which the ball is subjected to a periodic asymmetric
vibration in conjunction with a random noise. Here, as opposed to that of a fixed external force, the rolling velocity decreases
with the strength of the noise suggesting a progressive fluidization of the interface. A state (K) and rate (V) dependent friction model is able to explain both the evolution of the displacement fluctuation as well as the sigmoidal
variation of the drift velocity with K. This research sets the stage for studying friction in a new way, in which it is submitted to a noise and then its dynamic
response is studied using the tools of statistical mechanics. Although more works would be needed for a fuller realization
of the above-stated goal, this approach has the potential to complement direct measurements of friction over several decades
of velocities and other state variables. It is striking that the non-Gaussian displacement statistics as observed with the
stochastic rolling is similar to that of a colloidal particle undergoing Brownian motion in contact with a soft microtubule. 相似文献
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Lattice Boltzmann simulation of behaviour of particles moving in blood vessels under the rolling massage 下载免费PDF全文
The rolling massage is one of the most important manipulations in
Chinese massage, which is expected to eliminate many diseases. Here,
the effect of the rolling massage on a pair of particles moving in
blood vessels under rolling massage manipulation is studied by
the lattice Boltzmann simulation. The simulated results show that
the motion of each particle is considerably modified by the
rolling massage, and it depends on the relative
rolling velocity, the rolling depth, and the distance between
particle position and rolling position. Both particles'
translational average velocities increase almost linearly as
the rolling velocity increases, and obey the same law. The increment of
the average relative angular velocity for the leading particle is
smaller than that of the trailing one. The result is helpful for
understanding the mechanism of the massage and to further develop the
rolling techniques. 相似文献
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