Evacuation from a classroom considering the occupant density around exits

An existing cellular automaton evacuation model is modified to simulate an evacuation experiment conducted in a classroom with obstacles. In the modified model, the impact of the occupant density around exits on human behavior in evacuation is considered. The simulation and experimental results prove that this improvement makes sense, because besides the spatial distance to exits, people may also choose the exit according to the occupant density around exits. The distribution of individual evacuation times as a function of initial positions and the dynamics of the evacuation process are studied. Comparison between the experimental and simulation results shows that the model can reproduce the experiment well. The improvement of the CA model is useful for further study.     

Simulation of pedestrian counter-flow with right-moving preference

People prefer to walk on the right-hand side of the road for physical and social reasons. In this paper, pedestrian counter-flow in a channel is simulated with the Cellular Automata (CA) Model, with focus on right-preference. Two types of pedestrians are taken into account, walking leftward and rightward along the channel. Circular and open boundaries are adopted respectively. The right-preference intensity, k, is introduced, defined as the ratio of the right-moving probability to left-moving probability. In simulations, the dynamical transition between fluid and jammed phase is presented. With a fixed k, the critical density is independent of the channel size. According to research results on physiology and sociology [O. Guentuerkuen, Nature 421 (2003) 711; M. Reiss, G. Reiss, Percept. Mot. Skill 85 (1997) 569; M.C. Corballis, Psychol. Rev. 104 (1997) 714], k=1,2,8 have been discussed, and k=8 is satisfied in this work. Furthermore, simulation results are compared with the ideal calculation, and other researchers’ experiments [M. Isobe, T. Adachi, T. Nagatani, Physica A 336 (2004) 638]. It is found that right-preference is effective when the density is below critical. The model is shown to be useful to simulate and analyze this situation numerically.     

Design of $n$-dimensional multi-scroll Jerk chaotic system and its performances

Based on three-order Jerk and high-order Jerk chaotic systems, a general approach is proposed to generate $n$-dimensional multi-scroll Jerk chaotic attractors via nonlinear control. Dynamics of the $n$-dimensional multi-scroll Jerk chaotic systems are analyzed by means of the largest Lyapunov exponent and multi-scale permutation entropy complexity. As an experimental verification, four-dimensional Jerk chaotic attractors are implemented by analog circuits. Results of the numerical simulation are consistent with that of the hardware experiments. It shows that the method of obtaining complex Jerk chaotic attractors is effective.     

无限时滞的非线性随机泛函微分方程

本文考虑了无限时滞的非线性随机泛函微分方程,作者在局部利普希茨条件和非线性增长条件下证明了全局解的存在唯一性,矩指数稳定性和渐近稳定性.     

Thermal distortion and birefringence in repetition-rate plasma electrode Pockels cell for high average power

We numerically study thermally induced birefringence and distortion in plasma electrode Pockels cell based on KD*P as the electro-optic material. This device can repetitively operate under the heat capacity mode.Simulation results indicate that the excellent switching performances and low wave-front distortion are achieved within several tens seconds working time at average power in excess of 1 kW.     

Slowly Removing Surface Ligand by Aging Enhances the Stability of Pd Nanosheets toward Electron Beam Irradiation and Electrocatalysis

Surface ligands play an important role in shape-controlled growth and stabilization of colloidal nanocrystals. Their quick removal tends to cause structural deformation and/or aggregation to the nanocrystals. Herein, we demonstrate that the surface ligand based on poly(vinylpyrrolidone) (PVP) can be slowly removed from Pd nanosheets (NSs, 0.93±0.17 nm in thickness) by simply aging the colloidal suspension. The aged Pd NSs show well-preserved morphology, together with significantly enhanced stability toward both e-beam irradiation and electrocatalysis (e.g., ethanol oxidation). It is revealed that the slow desorption of PVP during aging forces the re-exposed Pd atoms to reorganize, facilitating the surface to transform from being nearly perfect to defect-rich. The resultant Pd NSs with abundant defects no longer rely on surface ligand to stabilize the atomic arrangement and thus show excellent structural and electrochemical stability. This work provides a facile and effective method to maintain the integrity of colloidal nanocrystals by slowly removing the surface ligand.     

Raman散射探测南京地区气溶胶光学特性

利用位于中国气象局南京综合观测基地的Rayleigh-Raman-Mie激光雷达Raman通道实测数据反演分析南京北郊气溶胶光学特性。在反演计算消光系数的过程中发现Raman信号波动很大、起伏很多,对我们反演结果带来了很大的困难,导致消光系数值波动范围达到-0.1~0.4km~(-1)。经过反复试验计算,用小波去噪解决这个问题,并将其反演结果与同一时刻同一仪器不同通道(Mie通道)反演结果进行对比,2011年3月30日晴天条件下二者消光系数都在0.05km~(-1)左右,它们的趋势具有很好的一致性,表明小波去噪能提高Raman散射反演气溶胶光学特性的准确性。     

The Raman spectroscopy of neutron transmutation doping isotope Germanium nanocrystals embedded in SiO2 matrix

We have succeeded in doping arsenic (As) impurities into isotope germanium nanocrystals (nc-⁷⁴Ge) uniformly dispersed in a SiO₂ matrix by using the neutron transmutation doping (NTD) method. The samples’ inner structural transmutation is studied by combining Raman scattering, X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS) and Transmission electron microscope (TEM) methods. The Raman spectrum of the doped sample exhibits a relative intensity increase of the low frequency tail, blue shift of the main Raman peak (∼300 cm⁻¹) and a high frequency tail, while the undoped sample does not. Together with the XRF, XPS and TEM, we believe that the relative intensity increase of the low frequency tail arises from an increase of amorphous ⁷⁴Ge (a-⁷⁴Ge) induced by the irradiation damage. The blue shift of the main Raman peak comes from the mismatch of the crystal lattice which arose from the As impurity introduction. And the high frequency tail is due to transmuted-impurities (As) in the nc-⁷⁴Ge which was introduced by NTD.     

高功率固体激光驱动器污染控制及片状放大器洁净度改进

针对高功率固体激光驱动器的安全运行,提出了覆盖驱动器建设全过程的污染控制方法,详细介绍了洁净清洗、洁净检测、洁净保护等保障污染控制效果的技术手段,并介绍了神光-Ⅲ主机装置片状放大器洁净度提升所采取的技术途径,以及片状放大器光照清洗实验中气溶胶等级随闪光灯照射次数的变化情况。实验结果表明,神光-Ⅲ主机装置的洁净水平与美国国家点火装置(NIF)接近且优于其他同类装置,洁净度的大幅提升为装置的安全运行提供了有力保障。