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T. Dagaeff 《Journal of statistical physics》1996,83(1-2):39-70
We discuss Liouville's theorem for nonsmooth integrable systems of the billiard type and give a scheme of calculation of angle-action variables for the flow. We also deal with the problem of pseudointegrability. We discuss the relationship between the continuous-time (flow) and the discrete-time (map) approaches. We treat all these aspects through a specific billiard—a wedge embedded in a two-dimensional isotropic harmonic potential. Varying the parameters provides two integrable and two pseudointegrable cases. It turns out that the dynamics of one of the latter is indeed integrable in a certain sense. We also address the problem of applying perturbation theory. 相似文献
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采用绝热近拟和绝热变分近似两种方法,计算了均匀强磁场(10≤β≤1000)中H2^+的σg,πu,δg,Φu,γg,ηu态的能有有原子核间的平衡距离,并与前人的结果进行了比较。 相似文献
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An effective potential method for the calculation of hydrogen molecule ion energy in a strong magnetic field 下载免费PDF全文
Using the adiabatic approximation and adiabatic variational approximation with an effective potential, the total energies and the equilibrium internuclear separations of H2+ ion in states σg, πu, δg, φu, γg, ηu in strong magnetic fields have been calculated. Our results reproduced those obtained by Vincke and Baye (Vincke M and Baye D 1985 J. Phys. B: At. Mol. Phys. 18 167), which are considered the most reliable. We found a basic function with better convergence than the Landau functions. 相似文献
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Dynamical properties are studied for escaping particles, injected through a hole in an oval billiard. The dynamics is considered for both static and periodically moving boundaries. For the static boundary, two different decays for the recurrence time distribution were observed after exponential decay for short times: A changeover to: (i) power law or; (ii) stretched exponential. Both slower decays are due to sticky orbits trapped near KAM islands, with the stretched exponential apparently associated with a single group of large islands. For time dependent case, survival probability leads to the conclusion that sticky orbits are less evident compared with the static case. 相似文献
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将导电的液体置于磁场中,使导电液体中浮力驱动的自然对流减弱甚至消失,在导电液体中制造出了二级微重力效应,将这种情况称为磁场微重力效应.通过研究导电液体自然对流驱动力的无量纲Grashof数的变化,发现微重力效应的水平可以用公式gm=(β0/βm)(ν0 /νm)2g0 计算,如果略去一次项,则可用gm=(ν0 /νm)2g0来估算.测量研究了不同磁场条件下硅熔体的磁黏度,估算不同磁场强度对应的磁场微重力水平后,发现估算结果与实验结果基本符合.
关键词:
磁场
二级微重力效应
Grashof数
微重力水平 相似文献
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根据磁多极场的对称性,首先导出了磁多极场磁场分量的泰勒级数展开式,定义了磁多极场的场参数,然后根据毕奥-萨伐尔定律,导出了马鞍型磁多极场线圈的场参数理论计算公式.对各个场参数数量级的大小进行了分析,找出了场参数的递推规律,给出了场参数高阶导数的计算方法,从而能够准确计算整个空间的磁场值.还从简单单根导线计算结果过渡到多根导线或具有某种连续分布的情况. 这对于磁二极场、磁四极场、磁六极场等的应用提供了可靠的理论依据.
关键词:
磁多极场
场参数
马鞍型线圈 相似文献
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We calculate the cross-section of the inverse beta decay process,v
e+n → p+e, in a background magnetic field which is much smaller than m
p
2/e
. Using exact solutions of the Dirac equation in a constant magnetic field, we find the cross-section for arbitrary polarization
of the initial neutrons. The cross-section depends on the direction of the incident neutrino even when the initial neutron
is assumed to be at rest and has no net polarization. Possible implications of the result are discussed. 相似文献
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The effect of a weak magnetic field on the diffusion of noninteracting electrons in a disordered system is studied in a nonlinear-model context. The effective Lagrangian describing the soft modes of the system in the weak field limit is derived. The result does not have the simple form that has been suggested by several authors. Therefore the crossover of the system under a weak perturbing magnetic field is not analogous to that found in spin systems. 相似文献
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Based on the thermodynamic potential function of Fermi gas
in a strong magnetic field, using the thermodynamics method, the
integrated analytical expressions of thermodynamic quantities of the
system at low temperatures are derived, and the effects of the
magnetic field on the statistic properties of the system are
analysed. It is shown that, as long as the temperature is not zero, the
effects of the magnetic field on the thermodynamic quantities of the
system contain both oscillatory and non-oscillatory parts. For the
non-oscillatory part, compared with the situation of Fermi gas in a
weak magnetic field, the influence of the magnetic field on the
thermodynamic quantities is not exactly the same. For the
oscillatory part, the period and amplitude of the oscillation are
all related to the magnetic field. Due to the oscillation, the chemical
potential may be greater than Ferim energy of the system, but the
oscillation does not affect the thermodynamic stability of the
system. 相似文献
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用计算机模拟的方法研究了地磁场中带电粒子的运动特性,绘制了粒子轨迹曲线,对粒子运动进行了分析,解释了地磁场的磁瓶效应和辐射带. 相似文献
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F. Y. Wu 《Journal of statistical physics》1985,40(5-6):613-620
A closed-form expression is obtained for the free energy per site of the Ising model on the triangular lattice in a nonzero magnetic field and with two- and three-site interactions. The solution is valid along a trajectory in the parameter space, and is derived using a method of exact decimation. A criterion determining the validity of the decimation method is also established. 相似文献
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Bohlin transformation for a circular singular oscillator in a constant magnetic field is considered. It is shown that this transformation leads to a two-dimensional Kepler problem with an additional centrifugal potential from the constant magnetic field whose strength decreases inversely proportional to the distance from the center of attraction of the system. The energy spectrum of the considered system is obtained. 相似文献
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运用理论解析和数值模拟的方法,研究强磁场中Fermi气体在低温下的稳定性及顺磁性, 分析温度、磁场对稳定性及磁化率的影响.研究结果显示,强磁场引起系统稳定性的改变, 这种改变与温度有关,而温度对稳定性改变及磁化率的影响又与自由气体的化学势即粒子数密度有关. 当自由系统的化学势为偶数时,磁场弱化系统的稳定性,温度升高可降低系统的磁化率; 当自由系统的化学势为奇数时,磁场强化系统的稳定性,温度升高可增大系统的磁化率. 升高温度,可以弱化磁场对系统稳定性的影响;加强磁场,可以使得系统稳定性的改变发生振荡, 使系统磁化率的振荡中心下移. 相似文献