Simulation of pedestrian evacuation strategies under limited visibility

Evacuation process under limited visibility is different from that under good visibility. To investigate the evacuation efficiency under limited visibility, different evacuation strategies including walking along the wall (S1), following the average movement direction (S2) and following the average position (S3) are proposed in this paper. Performances of these strategies under different visibilities, densities and exit widths are compared based on a revised social force model. Simulation results show that strategy S1 is more effective at low densities while strategy S2 and S3 are more efficient at high densities. It is noted that strategy S2 outperforms S3 under the same condition. In addition, strategy S1 is not sensitive to the change of exit width due to the movement mode of walking along the wall, while the following strategies (S2 and S3) have a better performance under the wide exit condition. The evacuation time for different proportions of pedestrians adopting one strategy in the mixed strategy situation is investigated and the optimal mixture proportion is also discussed. This study provides a new insight into the effect of different evacuation strategies on pedestrian evacuation, which is helpful for evacuees or organizers of public events to make an efficient evacuation plan under limited visibility.     

深陷阱对有机磷光双掺杂体系电致发光器件效率衰退的影响

研究利用溶液法制备的有机磷光双重掺杂体系电致发光器件的光致发光特性与电致发光特性,并研究了在这种体系中深能级陷阱导致的器件效率衰退现象。首先利用紫外光谱仪和光致瞬态寿命测试系统对基于旋涂法制备的以宽带隙材料4,4’-bis(N-carbazolyl)-1,1’-biphenyl（CBP）为主体,绿色磷光材料tris(2-phenylpyridine) iridium(Ⅲ)（Ir(ppy)₃）和红色磷光材料tris(1-phenylisoquinolinato-C2,N)iridium(Ⅲ)（Ir(piq)₃）为客体材料的薄膜进行了光致发射光谱测试和薄膜在Ir(ppy)₃发光峰516 nm处的光致发光寿命测试,实验发现在Ir(ppy)₃掺杂比例保持定值时,随着深能级掺杂材料Ir(piq)₃的引入,其光致发光光谱中Ir(ppy)₃的相对发光强度减弱且发光寿命变短,当Ir(piq)₃掺杂浓度继续提高时,薄膜光致发光光谱基本保持不变且Ir(ppy)₃的发光寿命基本不变。实验说明在低浓度掺杂下两者的三线态能级之间存在着能量传递,但当掺杂浓度达到高浓度时,能量传递主要来自于主客体之间的传递,两者作为独立的发光中心发光。然后利用溶液法制备了发光层分别为CBP∶Ir(ppy)₃,CBP∶Ir(ppy)₃∶Ir(piq)₃和CBP∶Ir(ppy)₃∶PTB7的三组器件,器件结构为ITO/PEDOT∶PSS/Poly-TPD/EML/TPBi（15 nm）/Alq₃（25 nm）/LiF（0.6 nm）/Al（80 nm）。在Ir(ppy)₃和Ir(piq)₃共掺杂器件和Ir(ppy)₃单掺杂器件的对比实验中发现,加入一定比例的深能级材料后,器件的电致发光光谱发生改变,Ir(piq)₃的相对发光强度增强,器件发光效率下降且效率滚降现象明显。通过对器件进行J-V测试,发现在Ir(ppy)₃单掺杂器件中陷阱填充电流随着掺杂材料浓度的提高而提高,但在加入等浓度深能级材料Ir(piq)₃后,陷阱填充电流基本保持一致。瞬态电致发光测试表明,随着Ir(ppy)₃掺杂比例的提高,器件内由于陷阱载流子释放而产生的瞬时发光强度降低,这是由于Ir(ppy)₃具有一定的传导电荷作用,会减少器件中的陷阱载流子,这进一步说明了具有较深能级的Ir(piq)₃是限制载流子的主要能级陷阱。同时发现随反向偏压的增大,瞬态发光强度增大且发光衰减加速,这是因为位于深能级陷阱的载流子在高电压下被释放,重新复合发光,说明深能级陷阱的确限制住了大量载流子,而由于主体三线态激子具有较长的寿命,激子间相互作用产生的单线态激子在高反压下解离,从而引起三线态激子-极化子相互作用的加剧,导致发光衰减加速。在窄带隙聚合物材料PTB7与Ir(ppy)₃共掺杂器件实验中发现,随着PTB7掺杂浓度提高,陷阱浓度变大且器件效率降低,具有较深能级的PTB7成为了限制载流子的深能级陷阱。因此说明在双掺杂有机磷光电致发光器件中,深能级材料会成为限制载流子的能级陷阱,引起载流子大量堆积,从而导致三线态激子与极化子相互作用加剧,使器件的发光效率衰退。     

价格数量折扣下多阶段报童问题的在线策略

价格数量折扣可以提高订购量, 是库存决策中的一个重要因素. 特别地, 当订购量达到一定水平时, 价格折扣才会发生. 应用理论计算机科学兴起的弱集成算法, 研究具有这种价格数量折扣的多阶段报童问题的在线策略. 弱集成算法是一种在线序列决策算法, 其主要特点是不对未来输入做任何统计假设, 克服了报童问题研究中需要对需求做概率假设的困难. 主要将弱集成算法应用到固定订购量的专家策略, 给出了价格数量折扣下多阶段报童问题的具体在线策略;得到了该在线策略相对于最优专家策略的理论保证. 进一步将回收价值和缺货损失费引入, 给出了推广的在线策略及其理论结果. 最后应用数值算例说明了给出的在线策略具有较好的竞争性能.     

基于动态分级和邻域反向学习的改进粒子群算法

针对粒子群算法容易陷入局部最优解的问题,提出了一种基于动态分级和邻域反向学习的改进粒子群算法.该算法通过构建动态分级机制,将种群中的粒子动态地划分成3个等级,对不同等级内的粒子采取不同的扰动行为,使得粒子在增强种群多样性的同时保持向全局最优方向进化;采用粒子智能更新方式,提高了粒子的搜索能力;引入动态邻域反向学习点建立全局搜索策略,促使种群快速寻优.最后,利用多种典型测试函数对该算法进行仿真实验,结果表明,与其他几种优化算法相比,本算法具有较好的收敛性和稳定性.     

无标度复杂网络负载传输优化策略

提出了一种能够显著提高无标度复杂网络负载传输性能的优化路由策略.实现了负载在核心节点与边缘节点间的合理分配.分析表明该策略使得网络的负载处理能力正比于网络规模的平方,而与单个节点的度值无关.实验结果显示优化路由策略在保持了最短路由策略小世界效应的同时,成倍地提升了网络的负载传输能力,且随着网络平均节点度的增加其优势越趋显著.此外,与有效路由策略的比较进一步验证了优化路由策略的优异性能. 关键词： 优化路由策略 复杂网络 负载传输 网络阻塞     

A New Nonmonotonic Trust Region Algorithm for A Class of Unconstrained Nonsmooth Optimization

This paper presents a new trust region algorithm for solving a class of composite nonsmooth optimizations. It is distinguished by the fact that this method does not enforce strict monotonicity of the objective function values at successive iterates and that this method extends the existing results for this type of nonlinear optimization with smooth, or piecewise smooth, or convex objective functions or their composition. It is proved that this algorithm is globally convergent under certain conditions. Finally, some numerical results for several optimization problems are reported which show that the nonmonotonic trust region method is competitive with the usual trust region method.     

基于小波分解和进化策略的图像融合方法

提出了一种基于小波分解和进化策略相结合的多聚焦图像融合方法。该方法首先对不同聚焦点图像进行无下采小波分解，并分别将其各方向、各尺度的高频信息进行叠加，然后依据它们在高频信息叠加层上对应的局部区域能量的差异，采用进化策略进行区域划分，进而实现分区域融合。实验结果表明所提出的方法比小波变换法具有更好的融合效果。     

Lagrange-SQP Techniques for the Control Constrained Optimal Boundary Control for the Burgers Equation

A Lagrange-Newton-SQP method is analyzed for the optimal control of the Burgers equation. Boundary controls are given, which are restricted by pointwise lower and upper bounds. The convergence of the method is proved in appropriate Banach spaces. This proof is based on a second-order sufficient optimality condition and the theory of Newton methods for generalized equations in Banach spaces. For the numerical realization a primal-dual active set strategy is applied. To illustrate the theoretical investigations, numerical examples are included. Moreover, a globalization technique for the SQP method is tested numerically.     

An Algorithm Constructing Solutions for a Family of Linear Semi-Infinite Problems

A family of linear semi-infinite problems depending on a parameter is considered. For fixed , a sensitivity analysis of the problem solution is carried out and rules constructing the solutions of this family for in a right-side neighborhood of ₀ are described. Results on the one-sided derivatives of the solution with respect to the parameter are presented. On the basis of the results, an active-set-strategy and a path-following algorithm are suggested.