Effective suppression of beta oscillation in Parkinsonian state via a noisy direct delayed feedback control scheme

This work explores the function of the noisy direct delayed feedback(NDDF)control strategy in suppressing the pathological oscillations in the basal ganglia(BG)with Parkinson’s disease(PD).Deep brain stimulation(DBS)alleviates the PD state fantastically.However,due to its unclear mechanism and open-loop characteristic,it is challenging to further improve its effects with lower energy expenditure.The noise stimulus performs competitively in alleviating the PD state theoretically,but it cannot adapt to the neural condition timely and automatically due to its open-loop control scheme.The direct delayed feedback(DDF)control strategy is able to disturb excessive synchronous effectively.Therefore,the NDDF control strategy is proposed and researched based on a BG computational model,which can reflect the intrinsic properties of the BG neurons and their connections with thalamic neurons.Simulation results show that the NDDF control strategy with optimal parameters is effective in removing the pathological beta oscillations.By comparison,we find the NDDF control strategy performs more excellent than DDF in alleviating PD state.Additionally,we define the multiple-NDDF control strategy and find that the multiple-NDDF with appropriate parameters performs better than NDDF.The obtained results contribute to the cure for PD symptoms by optimizing the noise-induced improvement of the BG dysfunction.     

Evolutionary algorithm for optimization of multilayer coatings

In this paper, a new evolutionary algorithm, the well-known imperialist competition algorithm, is proposed for optimizing the optical thin-films. In this method, the process is modeled of the competition between countries as imperialists and their colonizing of others as colonies. This algorithm could be an appropriate alternative to some of the more popular algorithms for optimizing the optical thin-films for good performance. The polarizer and edge filter for example are designed by using the imperialist competition algorithm method and the results are compared with those from two optimization high-performance methods: the genetic algorithm and differential evolutionary algorithm. Based on these results,the performance of the imperialist competition algorithm method shows that this algorithm is not sensitive to the change of its parameters and it can be an important advantage for quickly achieving a global optimal point. On the other hand the results show a better ratio of P-polarization transmittance to S-polarization transmittance in the design of a 1540-nm polarizer, which is more appropriate than the results from the other two methods. In the second design, an edge filter with a lower number of layers and more uniform bandpass spectrum than the counterparts of those methods is obtained. These results indicate that the imperialist competition algorithm is a robust method for optical thin-film designs.     

ALE计算中基于声速分布的网格优化技术

基于声速分布,提出一种拉氏流体力学计算中大变形网格优化的数值技术.该方法不但可以优化网格的几何形状且可以提高拉氏流体计算的时间步长.介绍基于声速分布的网格松弛泛函、修正梯度流方程的推导、离散和求解方法,启动/终止网格优化过程的条件,及基于这种网格优化方法的ALE算法.给出Rayleigh-Taylor不稳定性问题等数值算例,用以证明该方法的有效性.     

Improvement of Photoluminescence of Perovskite CH_3NH_3Pb I_3 by Adding Additional CH_3NH_3I during Grinding

The organic-inorganic hybrid perovskite CH_3NH_3PbI_3 has been a good candidate for many optoelectronic applications such as light-emitting diodes due to its unique properties.Optimizing the optical properties of the CH_3NH_3PbI_3 material to improve the device performance is a hot topic.Herein,a new strategy is proposed to enhance the light emission of CH_3NH_3PbI_3 phosphor effectively.By adding the reactant CH_3NH_3I powder in an appropriate proportion and simply grinding,the emission intensity of CH_3NH_3PbI_3 is greatly improved.The advantages of the proposed method are swiftness,simplicity and reproducibility,and no requirement for a complex organic ligand.The mechanism of this phenomenon is revealed by x-ray diffraction,scanning electron microscopy,energy dispersive spectroscopy,photoluminescence,and temperature-dependent photoluminescence.This study offers a unique insight for optimizing the optical properties of halide perovskite materials.     

激光镊子拉曼光谱法优化红法夫酵母合成虾青素条件

用激光镊子拉曼光谱法优化红法夫酵母生产虾青素的条件。首先,将红法夫酵母细胞拉曼光谱与虾青素标准品溶液拉曼光谱进行对比,找出定量虾青素的拉曼特征峰;然后对照红法夫酵母生长曲线与不同时间点红法夫酵母细胞内虾青素含量曲线,进行发酵时间的优化;最后将红法夫酵母分别用不同氮源、碳源培养基培养,对比其细胞的虾青素拉曼特征峰强度,最终优化培养基。由实验可得,适宜定量虾青素的拉曼特征峰是1520cm-1峰;最佳发酵时间为72h;最佳优化培养基氮源含硫酸铵4g/L+硝酸钾4g/L,碳源含蔗糖60g/L。从上述结果可知,用激光镊子拉曼光谱法对红法夫酵母合成虾青素的条件进行优化,充分发挥了其操作简便、耗时短、样品用量少、对样品无损伤等优势,使所得结果更准确可信。因此,激光镊子拉曼光谱法是红法夫酵母细胞合成虾青素条件优化的理想选择。     

超结构换热器网络综合优化的遗传/模拟退火算法-Ⅱ.遗传/模拟退火算法及应用

本文提出了用于换热器网络综合的改进的遗传/模拟退火算法.最优综合的模型基于本文第一部分所提出的通用解方法.所采用的遗传算法结合了模拟退火算法和爬山优化算法,同时引进精英策略和结构变异策略以增强算法的搜索能力.采用本文提出的算法对文献提出的算例进行了计算并得到了更好的结果.     

自适应混沌蚁群径向分析算法求解重力辅助导航匹配问题

针对现有重力导航匹配算法的匹配精度、匹配率受惯导初始位置误差影响较大以及实时性较差等不足,提出了一种基于自适应混沌蚁群径向分析的实时重力辅助导航匹配算法,新算法引入改进的连续域蚁群算法进行优化模型求解,通过进行连续域蚁群算法的信息素的自适应调整,同时对蚁群算法的搜索策略、计算参数、局部信息素进行混沌自适应处理,最终达到提高算法搜索效率、匹配率、抗噪性能的效果,实验结果表明,新算法对惯导初始误差不敏感,匹配率高,实时性强。     

基于混合群智能优化算法的混沌系统参数估计

混沌系统的未知系统参数估计是实现混沌控制和同步的首要问题,通过构造一个合理的适应度函数,可将其转化为一个多维搜索空间的优化问题.提出一种融合改进骨干粒子群算法与改进差分进化算法的混合群智能优化方法来解决上述优化问题.对骨干粒子群算法中的粒子位置更新机制以及差分进化算法中的变异操作、交叉操作、交叉概率因子的设计等进行改进,有效兼顾了种群的多样性与算法的收敛性.在此基础上,讨论骨干粒子群优化算法与差分进化的融合优化策略,实现两个算法的协同进化,进一步提高算法的综合优化性能.用6个基准测试函数以及Lorenz混沌系统为例进行仿真实验,结果表明该方法具有全局寻优能力强、收敛速度快、搜索精度高、稳健性好等优点.     

Numerical analysis for four-wave mixing based wavelength conversion of differential phase-shift keying signals

We numerically investigate the main constrains for high efficiency wavelength conversion of differential phase-shift keying （DPSK） signals based on four-wave mixing （FWM） in highly nonlinear fiber （HNLF）. Using multi-tone pump phase modulation techniques, high efficiency wavelength conversion of DPSK signals is achieved with the stimulated BriIlouin scattering （SBS） effects effectively suppressed. Our analysis shows that there is a compromise between conversion efficiency and converted idler degradation. By optimizing the pump phase modulation configuration, the converted DPSK idler＇s degradation can be dramatically decreased through balancing SBS suppression and pump phase modulation degradation. Our simulation results also show that these multi-tone pump phase modulation techniques are more appropriate for the future high bit rate systems.     

A greedy-navigator approach to navigable city plans

We use a set of four theoretical navigability indices for street maps to investigate the shape of the resulting street networks, if they are grown by optimizing these indices. The indices compare the performance of simulated navigators (having a partial information about the surroundings, like humans in many real situations) to the performance of optimally navigating individuals. We show that our simple greedy shortcut construction strategy generates the emerging structures that are different from real road network, but not inconceivable. The resulting city plans, for all navigation indices, share common qualitative properties such as the tendency for triangular blocks to appear, while the more quantitative features, such as degree distributions and clustering, are characteristically different depending on the type of metrics and routing strategies. We show that it is the type of metrics used which determines the overall shapes characterized by structural heterogeneity, but the routing schemes contribute to more subtle details of locality, which is more emphasized in case of unrestricted connections when the edge crossing is allowed.     

Sampling techniques for the estimation of the annual equivalent noise level under urban traffic conditions

This paper summarises 5 years of continuous noise measurements carried out at one of the most important squares in Valencia (Spain). The chosen square is a clear hotspot for traffic noise in a large city. The aim of this study is to determine the appropriate measuring time in order to obtain a 24-h noise level suitable to represent the annual equivalent level. Our findings allow us to reach a number of conclusions in terms of the most suitable urban traffic noise measurement techniques. A random day strategy for sampling is found to give a more accurate representation than a consecutive days strategy. If the sampling strategy involves measurements on randomly-chosen days, then at least 6 days should be used.     

少模多芯光纤的纤芯排布方法

提出一种3模12芯光纤的纤芯排布优化方法.在分析芯间串扰、弯曲半径阈值和相对纤芯多重性因子等特性后,给出了单圆形结构和方点阵结构的纤芯排布方法及优化方案.对于单圆形结构,在波长为1 625nm的情况下很难找到合适纤芯排布以使芯间串扰小于-30dB/100km并且使光缆截至波长小于1 530nm.对于方点阵结构,在波长为1 625nm,且弯曲半径大于弯曲半径阈值时,可使芯间串扰小于-30dB/100km,最大光缆截至波长不大于1 530nm,纤芯多重性因子可达到~15,这表明方点阵结构是一种比单圆形结构更适合3模12芯光纤的纤芯排布结构.     

Stabilization strategy of a car-following model with multiple time delays of the drivers

An extended car-following model with multiple delays is constructed to describe driver's driving behavior. Through stability analysis, the stability condition of this uncontrolled model is given. To dampen the negative impact of the driver's multiple delays (i.e., stability condition is not satisfied), a novel control strategy is proposed to assist the driver in adjusting vehicle operation. The control strategy consists of two parts:the design of control term as well as the design of the parameters in the term. Bifurcation analysis is performed to illustrate the necessity of the design of parameters in control terms. In the course of the design of parameters in the control term, we improve the definite integral stability method to reduce the iterations by incorporating the characteristics of bifurcation, which can determine the appropriate parameters in the control terms more quickly. Finally, in the case study, we validate the control strategy by utilizing measured data and configuring scenario, which is closer to the actual traffic. The results of validation show that the control strategy can effectively stabilize the unstable traffic flow caused by driver's delays.     

浓密视差图的快速提取

视差图的提取既是双目视觉研究的核心,也是双目视觉研究的难题。全面研究了基于归一化协方差区域相关快速提取浓密视差图的途径,从快速相关计算、数据结构优化和金字塔图像匹配策略三个方面加速了匹配过程,实现了浓密视差图的快速提取。     

一种非定常N-S方程并行求解设计

为了解决计算流体力学(CFD)中非定常计算与越来越大的计算量,并行计算已成为一种现实有效的选择.论文首先研究了一种并行区域分解策略,该策略简单而高效,但需要算法配合.为此,采用了一种与并行完全兼容的隐式方法DP-LUR方法.通过双时间步长法,将DP-LUR方法延伸应用到非定常计算中而不改变其原有的性质.最后分析了并行编程中的主要难点,提出解决方法,即采用中间数据分离节点下标与处理,并给出了并行程序的总体结构.     

Free-electron laser without inversion: gain optimization and implementation scheme

We consider a scheme of two noncollinear wigglers with an intermediate magnetic drift region, constituting a free-electron laser without inversion (FELWI). Two mechanisms of phase shifts in the drift region between the wigglers owing to a series of magnetic lenses can give rise to FELWI: velocity- and angle-dependent shifts. An appropriate combination of these shifts is shown to provide the conditions for amplification without inversion. The phase shifts optimizing the gain are found. A specific scheme for the drift region is suggested.     

输油管道运行优化研究

为了降低输油能耗,本文以输油管道热耗~电耗耦合费用为目标函数,建立了准周期性非稳态大气环境温度下,输油管道优化运行数学模型,编制了相应的软件。以庆~哈输油管道为例进行了优化计算。结果表明,该管道优化运行每年节约费用超过600万元,各加热站优化运行出口油温及压力都是年周期性变化的,且油温比大气温度延迟约2个月。因此,输油管道优化运行应该考虑温度延迟的影响。     

短腔自屏蔽核磁共振成像超导磁体的设计

本文提出了一种短腔自屏蔽核磁共振成像(MRI)超导磁体的设计方法.先将矩形截面螺线管线圈简化成截面为一个点的电流环,得到一个线性规划模型,采用线性规划的方法得到合适的线圈位置和电流大小,然后再利用遗传算法对线圈的截面形状进行优化,得到合适的线圈截面尺寸.线性规划的引入,减少了优化变量,降低了优化规模,结合遗传算法,使得短腔自屏蔽MRI超导磁体设计变得简单易行.文章最后给出了一个设计算例.     

Testing Transition State Theory on Kac-Zwanzig Model

A variant of the Kac-Zwanzig model is used to test the prediction of transition state theory (TST) and variational transition state theory (VTST). The model describes the evolution of a distinguished particle moving in a double-well external potential and coupled to N free particles through linear springs. While the Kac-Zwanzig model is deterministic, under appropriate choice of the model parameters the evolution of the distinguished particle can be approximated by a two-state Markov chain whose transition rate constants can be computed exactly in suitable limit. Here, these transition rate constants are compared with the predictions of TST and VTST. It is shown that the application of TST with a naive (albeit natural) choice of dividing surface leads to the wrong prediction of the transition rate constants. This is due to crossings of the dividing surface that do not correspond to actual transition events. However, optimizing over the dividing surface within VTST allows one to eliminate completely these spurious crossings, and therefore derive the correct transition rate constants for the model. The reasons why VTST is successful in this model are discussed, which allows one to speculate on the reliability of VTST in more complicated systems.