阻尼系统重特征对导数的计算

提出了一种计算阻尼系统重特征值及其特征向量导数的方法．该方法利用n维空间的特征向量计算特征对的导数,避免了状态空间中特征向量的使用,从而节省了计算量,提高了计算效率．最后以一个5自由度的非比例阻尼系统对所提方法进行了数值试验,数值结果表明方法是有效的．     

运用预饱和对HOESY实验灵敏度优化

二维异核NOESY(HOESY)内在的低灵敏度限制其在结构分析上的应用,利用¹H探测（反式探测）可以提高其灵敏度. 这里我们提出一种预饱和二维¹³C-¹H HOESY实验,利用异核之间的NOE增强效应,进一步提高实验的灵敏度. ¹H探测HOESY谱图中经常有严重的t₁噪声,可以通过脉冲梯度场相关选择和相位循环压制,得到改善的¹³C-¹H的NOE相关谱图.     

Numerical simulation of transient thermal field in laser melting process

Numerical simulation of thermal field was studied in laser processing. The 3-D finite element model of transient thermal calculation is given by thermal conductive equation. The effects of phase transformation latent are considered. Numerical example is given to verify the model. Finally the real example of transient thermal field is given.     

Quantum Dynamics of a Single Trapped Ion Interacting with Standing Laser Pulses

A classically chaotic system consisting of a Paul trapped ion and a sequences of standing laser pulses is treated quantum-mechanically. Under the circumstance of time-dependence, we derive the transition probability from the ion‘s motional state n to n‘, and find, in the first-order approximation, the classically chaotic character disappears.Theoretical analysis and numerical calculations show that by regulating the phase parameter Ф we can control thetransition probability. When Ф reaches some specific values, the transition from the state n to n‘ is forbidden and, for some laser periods, resonance occurs, which leads to the corresponding transitions between different motional states.The time-evolution of an initial motional state |ψz) just over one period is also studied in detail.     

Neutron Star Matter Including Delta Isobars

In this paper a new phase structure of neutron star matter including nucleons and delta isobars is presented. Particle fractions populated and pion condensations in neutron star matter are investigated in this model. The existence of the pion condensations can postpone the appearance of delta isobars. We found that both the pion condensation and reduce of the ratio of delta isobar to nucleons couplings can soften the corresponding equation of state. The maximum masses and their corresponding radii of neutron stars are calculated, and the obtained values are in observational region.     

Theoretical Description of the Third Order Parametric Wave Mixing in a Gas-Filled Capillary of Femto-Second Laser Pulse

The theoretical signal-pressure curves are calculated from approximate analytical solutions of the coupled equations describing the third order parametric wave mixing in a gas-filled capillary of femto-second laser pulses, The comparison with the corresponding experimental curves suggests that the following three factors exert important influences on the degree of fitting between the theoretical and experimental results: the walk-off, the phase modulation, and the third order harmonic of idler pulse.     

Geometric Phase of a Coupled System

In this contribution, my main attention is paid to the study of the geometric phase of a two-level system.Asymptotic expansion of the eigenvalue and analytic information are obtained. The results are illustrated with an application to a specific atomic system.     

Structure of a Phase-Separating System in the Presence of Oscillatory Particles

We numerically simulate the processing of the phase separation of the polymer blend-particle system under fluctuating fields by new discretization‘s form. Due to the presence of oscillatory particles which have an affinity for one of the components, the ordering mechanism of phase separation will be changed. By changing the oscillatory frequency ω and amplitude γ, we can find the formation of the striped structures either parallel or perpendicular to the oscillatory direction and obtain a diagram describing the orientational ordering of the domain structures.     

Kinetic Gaussian Model with Long-Range Interactions

In this paper dynamical critical phenomena of the Gaussian model with long-range interactions decaying as 1/r^d+δ (δ>0) on d-dimensional hypercubic lattices (d=1, 2, and 3) are studied. First, the critical points are exactly calculated, and it is found that the critical points depend on the value of δ and the range of interactions. Then the critical dynamics is considered. We calculate the time evolutions of the local magnetizations and the spin-spin correlation functions, and further the dynamic critical exponents are obtained. For one-, two- and three-dimensional lattices, it is found that the dynamic critical exponents are all z=2 if δ>2, which agrees with the result when only considering nearest neighboring interactions, and that they are all δ if 0<δ<2. It shows that the dynamic critical exponents are independent of the spatial dimensionality but depend on the value of δ.     

Phase shift of the population oscillation and population trapping

Using our recently developed time-dependent multilevel approach, we have calculated the phase shift of the population oscillation of the excited potassium atom in frequency-modulated fields when the modulation amplitude is suddenly changed. The numerical results are in good agreement with the measurements. A new way of realizing population trapping is suggested.