非高斯噪声对惯性棘轮中粒子负迁移率的影响

利用随机模拟方法研究了惯性棘轮中非高斯噪声对负迁移率的影响. 分别模拟了绝对负迁移率(ANM), 非线性迁移率(NNM) 和负微分迁移率(NDM) 等三种反常输运现象. 计算结果表明: 1) 在不同的参数空间里, 非高斯噪声参数q 能够增强或者削弱ANM, 诱导NNM 和NDM; 2) 当q 较大时, 反常输运现象转化为正常输运; 3) 随着q 逐渐增大, 平均速度- 关联时间特性曲线朝着关联时间较小的方向移动并且其峰值逐渐减小. 关键词： 反常输运 负迁移率 非高斯噪声     

Uphill anomalous transport in a deterministic system with speed-dependent friction coefficient

We investigate the transport of a deterministic Brownian particle theoretically, which moves in simple onedimensional, symmetric periodic potentials under the influence of both a time periodic and a static biasing force. The physical system employed contains a friction coefficient that is speed-dependent. Within the tailored parameter regime, the absolute negative mobility, in which a particle can travel in the direction opposite to a constant applied force, is observed.This behavior is robust and can be maximized at two regimes upon variation of the characteristic factor of friction coefficient. Further analysis reveals that this uphill motion is subdiffusion in terms of localization(diffusion coefficient with the form D(t) ~t~(-1) at long times). We also have observed the non-trivially anomalous subdiffusion which is significantly deviated from the localization; whereas most of the downhill motion evolves chaotically, with the normal diffusion.     

Statistical fluctuations in a saturation laser model with correlated noises

We study the effects of correlations between quantum and pump noises on fluctuations of the laser intensity in a saturation laser model. An approximative Fokker--Planck equation and analytic expressions of the steady-state probability distribution function (SPD) of the laser system are derived. Based on the SPD, the normalized mean, the normalized variance, and the normalized skewness of the steady-state laser intensity are calculated numerically. The results indicate that (i) the correlation strength \lambda of correlated noises always enhances the fluctuation of laser intensity; (ii) the correlation time \tau of correlated noises strengthens the fluctuation of laser intensity for the below-threshold case but \tau weakens it for the above-threshold case.     

用308nm准分子激光改变二氧化钛陶瓷的电导率

用３０８ｎｍ准分子激光对二氧化钛的陶瓷辐照，当能量密度高于阈值时，使其导电发生了显著的变化，室温下从原来的绝缘体转变为半导体。利用Ｘ射线衍射，Ｘ射线光电子能谱及显微分析等多种测试方法进行了分析，比较，稳定了该过程是由于高峰功率短脉冲的准分子激光对ＴｉＯ２的快速熔凝作用，导致了氧的缺位，引起了化学配比偏离。     

准分子激光对水松纸打标的研究

用适当能量密度的３０８纳米波长紫外激光对水松纸作用，获得了清晰可见的图案标记。分析了该打标过程的作用机理，通过实验得出了打标的能量阈值条件及优化条件。     

Effects of Correlations Between the Real and Imaginary Parts of Quantum Noise on Intensity Fluctuation for a Single-Mode Laser

We study the effects of correlations between the real and imaginary parts of quantum noise on the intensity fluctuation for a single-mode laser. The analytic expressions of the intensity correlation function C(r) and the associated relaxation time Tc in the case of a stable locked phase resulting from the cross-correlation λq between the real and imaginary parts of quantum noise are derived by means of projection operator method. Based on numerical computations it is found that the presence of cross-correlations between the real and imaginary parts of quantum noise causes the intensity fluctuation to increase. A slowing-down phenomenon exists in the sense that Tc increases as a function of |λq|. Thus the decay o[ intensity fluctuation becomes slower.     

Time Delay Induced Stochastic Resonance in One Species Competition Ecosystem without a Periodic Signal

One-species competition ecosystem with noise and time delay was investigated as not driven by a periodic force.The results show that the time delay is responsible for stochastic resonance of the system as delay time is smaller than critical point of the Hopf bifurcation.