摘要：To the Editor:Wake-up stroke(WUS)is the name given to an ischemic stroke that occurs primarily during night-time sleep and accounts for approximately 20%of all cases of acute ischemic stroke(AIS).Epidemiological studies have demonstrated a circadian distribution of AIS,with a higher frequency in the morning and a lower frequency during sleep.[1]It remains unclear whether WUS is a stochastic event or if a distinct pathophysiologic process,such as circadian rhythm disorder,differentiates WUS from daytime stroke(non-WUS).

摘要：结合当前国内外智库建设现状,针对大数据时代智库情报功能相对欠缺之处,提出了构建智库情报服务平台,拟为智库建设提供工作思路。文章首先探讨了智库研究与情报研究在理论上的契合关系,然后构建了智库情报服务平台模型,设计了智库情报服务平台的工作内容;最后提出了构建智库情报服务平台的措施,认为智库运行机制内含情报工作机制,智库建设必须强化其内在的情报工作机制。

摘要：Geomechanical parameters are complex and *** order to take this complexity and uncertainty into account,a probabilistic back-analysis method combining the Bayesian probability with the least squares support vector machine(LS-SVM) technique was *** Bayesian probability was used to deal with the uncertainties in the geomechanical parameters,and an LS-SVM was utilized to establish the relationship between the displacement and the geomechanical *** proposed approach was applied to the geomechanical parameter identification in a slope stability case study which was related to the permanent ship lock within the Three Gorges project in *** results indicate that the proposed method presents the uncertainties in the geomechanical parameters reasonably well,and also improves the understanding that the monitored information is important in real projects.

摘要：基坑支护设计优化一项重要而又复杂的问题,通过将支持向量机与微粒群算法结合,提出了基坑支护设计优化的新方法,并详细叙述了其实施过程;该方法用支持向量机表示支护设计参数与基坑安全系数之间的复杂非线性映射关系,提高了优化过程中基坑稳定性评价的效率,用微粒群算法作为优化工具,优化过程实施比较简单,并且具有很好的全局优化能力,最后,通过一个工程实例说明了该方法的有效性。

摘要：基于并行工程的思想 ,提出了一个面向后勤工程的产品设计评估系统。论述了系统的总体设计思想、体系结构及实施方法等。实现了从新的视角对产品设计的评价。

摘要：Plasmon induced transparency(PIT)in the transparent window provides new insights into the design of optical filters,switches and storage,and integrated *** slow light effect makes PIT applicable to both sensors and slow light ***,PIT can overcome the diffraction limit of light,which makes it possible to manipulate light on a half-wavelength scale and brings good news to the miniaturization of optical *** this paper,we first summarize the researches of PIT phenomenon based on metal-dielectric-metal(MDM)waveguide systems and analyze the physical mechanisms of PIT including bright-dark mode interactions and phase-coupling-induced ***,we review the applications of PIT in optical sensing,optical filtering,optical switching,slow light devices and optical logic *** last,we outline important challenges that need to be addressed,provide corresponding solutions and predict important directions for future research in this area.

摘要：相比于传统的1×N对称型多模干涉(Mult-Mode Interference ,MMI)分束器设计,提出了一种新型埋入式弱限制光波导分束器件.它的干涉区及输入输出波导采用倒锥形式,器件尺寸减小,且不均匀性与附加损耗也减小.以1×4的对称型MMI分束器为例,当只对干涉区采用倒锥形结构后,在TE偏振中心波长为1 .55μm时,器件长度减小了500μm,均匀性增加了0.131 dB,而附加损耗仅增加了0 .02 dB,波长响应较传统设计增加了40 nm.在此基础上,又在输入输出臂上也各增加倒锥形结构后,相比于传统设计附加损耗减小了0 .02 dB,均匀性增加了0 .139 dB,器件长度减小了500μm.改进后的器件具有优越的容差性.器件采用掺氟型聚合物材料进行优化设计,通过在合理范围内偏离输出波导位置,使输出光强达到最大值.

摘要：介绍了在用市政桥梁结构基于位移的抗震安全评估的步骤和方法。依据国内外普遍接受的结构抗震设计理念,以墩柱顶的位移延性系数、墩柱底截面钢筋的拉应变和混凝土的压应变为参数,通过比较结构的抗震能力和地震需求,提出了在用市政桥梁结构抗震安全评估标准。用基于位移的方法和评估标准,对北京5座在用市政桥梁进行了在设防烈度地震和罕遇地震作用下的抗震安全评估,为这些桥梁是否需要抗震加固提供了依据。

摘要：讨论了表面磁钢结构的永磁电机磁极形状的设计问题 .表面磁钢结构的永磁电机磁场波形由磁钢的形状确定 .如果磁场波形已知 ,通过求解电磁场反问题就可以获得理想的磁钢形状 .其求解过程一般是先转化为电磁场正问题 ,然后进行寻优叠代 .但在寻优过程中 ,利用传统寻优方法求解该问题难以获得满意结果 ,因此本文将遗传算法引入到电磁场反问题求解中来 ,并根据该问题的特点 ,提出了“基因子链最高位受限变异”以及“相邻基因子链相关变异”等概念 ,利用有限元方法与遗传算法相结合 ,对该电磁场反问题进行了寻优求解 。

摘要：为了调整全桥式串联谐振变换器的输出电压并消除其纹波,文中采用无源性控制方法对其进行建模与控制.首先建立串联谐振变换器的欧拉-拉格朗日模型;然后利用"注入阻尼使得系统稳定"的无源性控制思想和李亚普诺夫稳定性理论来设计一个非线性的无源性控制器.仿真和实验结果表明:在随机输入扰动、负载参数变化的情况下,输出电压和电感电流响应曲线发生跃变,受负载波动影响较大,但很快回到原来的平衡点;系统有稳定的可调整的输出电压,具有较强的鲁棒性、快速性和跟踪性,且纹波较小.