不同结构SOI交叉波导的损耗及串扰特性研究

利用高阶Pade近似的2D-BPM算法,对具有不同弯曲半径及交叉角度的SOI弯曲交叉波导的传输特性进行了模拟、分析和深入研究,发现交叉波导的串扰随弯曲半径及交叉角度增大而减小的规律.在此基础上,对由正弦弯曲、余弦弯曲以及圆弧弯曲三种弯曲波导构成的SOI交叉波导的损耗及串扰特性进行了分析比较.结果表明,由正弦弯曲构成的交叉波导传输损耗最小且串扰最小.     

非定常不定边界问题边界无法的若干进展

对于复杂的非线性工程问题的数值模拟,边界元法（ＢＥＭ）日益显示出优于区域解法的长处,特别是时间相关（需按时段逐步迭代推进）和含各种不定边界（造成可变区域,网络需不断重分）的情形,ＢＥＭ可显著减少存贮要求与计算量．针对非线性问题数值模拟的主要难点,即微分算子线性化,时间相关项与可动边界（非线性边条）的处理等,综述了国内外边界无法学术界的近期研究进展,总体目标是寻求一种适应多种微分算子、非线性迭代和时段推进计算效能高的稳定数值模式．      

施工期混凝土高拱坝已灌区温度回升解析

针对施工期高拱坝已灌区温度回升的现象,结合建设中的溪洛渡特高拱坝已灌区温度回升值进行统计分析,以及将蓄水前的已灌区混凝土块近似简化为混凝土平板问题,基于混凝土天然冷却或回升理论对已灌区温度回升现象进行解析,分析表明,当前高拱坝的封拱温度低于坝址年平均气温,不可避免地出现坝址年平均气温向已灌区进行缓慢温度倒灌,而且已灌区温度回升理论值与实测温度回升值较接近,由此认为,当前施工期高拱坝已灌区温度回升,主要原因应为外界环境气温向已灌区混凝土块的温度缓慢倒灌.     

Penta- and hexaruthenium carbonyl 'raft' complexes supported by monocarborane cage ligands

Reaction between [PPh4][closo-4-CB8H9] and [Ru3(CO)12] in refluxing toluene affords the unprecedented hexaruthenium metallacarborane salt [PPh4][2,3,7-{Ru(CO)3}-2,6,11-{Ru(CO)3}-7,11,12-{Ru(CO)3}-3,6,12-(micro-H)3-2,2,7,7,11,11-(CO)6-closo-2,7,11,1-Ru3CB8H6] (1a), which contains a planar Ru6 'raft' supported by a {CB8} monocarborane cluster. Addition of [CuCl(PPh3)]4 and Tl[PF6] to a CH2Cl2 solution of 1a results in simple cation replacement, forming the analogous [Cu(PPh3)3]+ salt (1b). The phenyl-substituted monocarborane [NEt4][6-Ph-nido-6-CB9H11] reacts with [Ru3(CO)12] in refluxing 1,2-dimethoxyethane to afford the pentaruthenium cluster species [N(PPh3)2][2,3,7-{Ru(CO)3}-3,4,8-{Ru(CO)3}-7,8-(micro-H)2-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H6] (2), after addition of [N(PPh3)2]Cl. Treatment of 2 with [CuCl(PPh3)]4 and Tl[PF6] in CH2Cl2 forms the zwitterionic complex [10,12-{exo-Cu(PPh3)2}-2,3,7-{Ru(CO)3}-3,4,8-{Ru(CO)3}-7,8,10,12-(micro-H)4-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H4] (3). Substitution of CO by PPh3 with concomitant cation replacement occurs on introduction of [AuCl(PPh3)], Tl[PF6], and PPh3 to a CH2Cl2 solution of 2, forming [Au(PPh3)2][2,3,7-{Ru(CO)2PPh3}-3,4,8-{Ru(CO)2PPh3}-7,8-(micro-H)2-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H6] (4). Crystallographic studies confirmed the cluster architectures in 1b, 2, and 3.     

One-pot synthesis of donor-acceptor [2]rotaxanes based on cryptand-paraquat recognition motif

Two novel cryptand-based [2]rotaxanes were synthesized by a facile one-pot reaction from three neutral precursors: easily accessible cryptand host 1 and commercially available 4,4'-bipyridine and 3,5-di-tert-butylbenzyl bromide. Their structures were confirmed by (1)H NMR, 2D NMR, HRMS and X-ray analysis. Moreover, two [2]pseudorotaxanes based on the same cryptand hosts and dibenzyl viologen guest 3 were also demonstrated both in solution and in the solid state, which are different from previously reported [3]pseudorotaxane-like complexes formed by dimethyl viologen guest 2 and the cryptands.     

Facile Preparation of Polymeric Dimers from Amphiphilic Patchy Particles

A straightforward strategy for assembling polymeric dimers from amphiphilic nanoparticles is reported. Amphiphilic polymeric nanoparticles with a mixed‐shell of PEO/P2VN blocks and a flexible core of PAA blocks are fabricated by a non‐covalent crosslinking method. Uniform polymeric dimers are efficiently and simply obtained via hydrophobic interactions under optimized conditions in selective solvent. The steric hindrance generated by reorganization of hydrophilic polymer brushes during the interparticle association is critical for morphological selectivity in the assembly. General applicability offers the possibility to organize functional NPs into superstructures with well‐defined geometry and association numbers.     

Subwavelength imaging enhancement through a three-dimensional plasmon superlens with rough surface

In this Letter we investigate the subwavelength imaging of a three-dimensional plasmon superlens based on the full vector wave simulations of optical wave propagation and transmission. The optical transfer functions are computed. Comparisons are made between the results of lenses with flat and periodic/random rough surfaces. We also study the problem of practical imaging system geometry using laser as an illumination source. Results show that the lens with periodic or random roughness can reduce the field interference effects, and provide improved focus on the transmission field and the Poynting flux. We illustrate that the subwavelength roughness in a plasmon lens can enhance the image resolution over a flat lens for both matched and unmatched permittivity conditions. The enhancement of resolution occurs because the introduced subwavelength roughness can amplify the evanescent wave components and suppress the surface plasmon resonance peaks.     

改进的K最短路径算法在通信网络中的应用

经典的K最短路径算法是最短路径算法中一个重要分支,它在交通网络的实时路径选择中起到了很重要的作用,为了将经典的K最短路径算法应用于通信网络中,我们对经典的K最短路径算法进行了改进.在求解K最大期望容量路径算法时,先对其进行权重转换,然后使用MPS算法;在求解K最大容量路径算法时,选取每个弧段源点,终点和弧段对应3个容量值最大的来进行标号;在求解K最大期望容量路径时,建立一系列的子网络,在每个子网络中先求出K最大可靠路径,对其容量进行排序,选出最小的,将大于该最小容量的所有弧集构成的网络定义为它的子网络,以此类推直到源点到目标点没有路径为止,对每个子网络中选取的K最大期望容量路径进行统一排序得到原网络中的K最大期望路径.通过网络通信实例,验证了算法的正确性和可行性.     

分形图形与激光全息防伪技术

利用分形图形具有无限可分和比例尺度上的自相似的特征以及可以产生无限变量重复码的特点，通过计算机控制激光双光束干涉光刻成点阵全息光栅，从而形成数字像素全息图．构造出分形图形的迭代函数系统框架，形成丰富多彩，变化多端的分形图形，以此对点阵全息光栅编码，光刻成分形数字像素全息图．     

Designed synthesis for some transition metal clusters involving bridging-sulfido ligand

Designed synthesis for some transition metal clusters involving bridging-sulfido ligands is reviewed. The basic concept with the use of reactive fragments as building blocks is described. It is shown that the sulfido ligands with lone-pair electrons and the unsaturated coordination sites play important roles in this rational synthesis. The relationship between the metallic coordination types of the sulfido ligands and their assembling activity in the compounds is summarized. Examples of the six kinds of unit construction with reactive fragments as building blocks are shown, indicating clearly that the unit construction is a reasonable way in the synthesis of transition metal clusters involving bridging sulfido ligands. Finally, the potential application of the unit construction schemes in the synthesis of transition metal clusters involving other bridging ligands is presented.