自由立体显示器中锯齿状交错狭缝光栅的设计

光栅式自由立体显示由于易存在莫尔条纹和串扰的问题而影响其显示效果.利用斜光栅可减轻莫尔条纹但增加了视点间的串扰.本文提出一种减轻莫尔条纹的光栅设计方法,同时对可视区域影响较小.设计中对光栅进行分段,并将相邻两段狭缝错开一定距离.该方法能减小通过同一狭缝看到两相邻子像素之间的黑条的比例,获得较宽且较淡的莫尔条纹,从而减轻了视觉干扰.仿真结果表明该光栅相比传统垂直光栅,莫尔条纹亮度下降了108.1%,而可视区域仅减小32.8%,具有较高的实用价值.     

Functionalized Hydrocarbon Belts: Synthesis,Structure and Properties

Hydrocarbon belts have drawn great attention because of their unique structures and tantalizing properties. Although a few belts and heteroatom-doped analogs have been synthesized, belt molecules containing non-hexagonal rings remain rare. Herein we report the construction and application of unprecedented zigzag-type hydrocarbon belts which contain functionalized eight-membered rings. The synthesis features fourfold intramolecular acylation reactions of resorcin[4]arene-derived intermediates, which affords C₄-symmetric tetrabenzobelt[4]arene[4]cyclooctatrienones. Stereoselective ketone reduction with LiAlH₄ and nucleophilic addition with alkynyllithiums provide the corresponding tetrahydroxylated belts. The tetraol and its methyl ether are powerful and selective hosts to form 2 : 1 and 1 : 1 complexes with cesium ion, respectively, with binding constants up to (1.71±0.33)×10¹¹ M⁻² and (1.50±0.16)×10⁶ M⁻¹. In addition, enantiopure C₄-symmetric belts can emit CPL with |g_lum| being around 0.01.     

Circumpentacene with Open-Shell Singlet Diradical Character

Circumacenes (CAs) are a distinctive type of benzenoid polycyclic aromatic hydrocarbons where an acene unit is completely enclosed by a layer of outer fused benzene rings. Despite their unique structures, the synthesis of CAs is challenging, and until recently, the largest CA molecule synthesized was circumanthracene. In this study, we report the successful synthesis of an extended circumpentacene derivative 1 , which represents the largest CA molecule synthesized to date. Its structure was confirmed by X-ray crystallographic analysis and its electronic properties were systematically investigated by both experiments and theoretical calculations. It shows a unique open-shell diradical character due to the existence of extended zigzag edges, with a moderate diradical character index (y₀=39.7 %) and a small singlet-triplet energy gap (ΔE_S-T=−4.47 kcal/mol). It exhibits a dominant local aromatic character with π-electrons delocalized in the individual aromatic sextet rings. It has a small HOMO–LUMO energy gap and displays amphoteric redox behavior. The electronic structures of its dication and dianion can be considered as doubly charged structures in which two coronene units are fused with a central aromatic benzene ring. This study provides a new route toward stable multizigzag-edged graphene-like molecules with open-shell di/polyradical character.     

变截面阻抗桩纵向振动问题积分变换解

利用拉普拉斯（Laplace)变换,将变截面阻抗桩振动的时域定解问题转换到频域的形式,求得了关于桩顶位移响应及速度响应的传递函数,然后利用求留数的方法求得了桩土系统的脉冲响应函数,利用脉冲响应函数求得了多种不同激振波形条件下（稳态正弦激励,瞬态半正弦激振及叠加有高频干扰波的瞬态半正弦激振等）的桩顶速度响应的表达式,并对桩土系统的频域特性作了深入的研究,得到了许多重要的结论。此外还将稳态正弦激振、态半正弦激振条件下的解与有关文献所采用分离变量法得到的解进行了对比,为两者的正确性提供了重要的证明。     

三峡工程移民迁建区灾害地质体改造与利用研究

三峡工程移民迁建区地质环境复杂 ,建设用地严重不足。如何在治理的基础上对滑坡等灾害地质体开发利用是一项风险极大 ,但具非常现实意义的课题。本文论述了预应力锚拉桩在库区大型滑坡防治中的应用成果 ,这种方法不仅能有效地控制滑坡体的稳定性 ,同时 ,也能根据移民工程要求提供适宜的建设用地 ;介绍了注浆方法对库区分布较广的以崩塌、滑坡、岩溶成因为主的崩滑堆积体的改造问题 ,它不仅可以大大降低移民迁建区地基与边坡处理的工程造价 ,也为库区灾害地质体的改造提供了范例 ;弃渣是库区极为突出的环境地质问题 ,不仅危害长江 ,也对移民迁建区构成严重威胁 ,本文介绍了巫山新城等利用加筋土技术处理弃渣 ,并大大增加建设用地的实例 ,由于该挡墙高达 5 6 m,超出了一般意义下的加筋土挡墙范畴 (通常不超过 2 0 m) ,因此出现了前缘筋带断裂和面板脱落问题 ,本文介绍了应用锚管注浆技术进行面板修复的设计 ,为复杂地质条件地区高加筋挡土墙的安全修建提供了经验.     

桩端后注浆灌注桩承载能力增强机理试验研究

为进一步研究灌注桩桩端后注浆承载机理, 对宁波某施工场地的4根灌注桩开展了现场试验研究. 4根灌注桩均采用自平衡方式加载, 以加载方式获得每根桩的Q—s曲线, 并通过桩身内部埋设的传感器得到加载期间桩身及桩底的应力数据, 根据应力分析研究桩身弯矩及桩侧摩阻力的变化. 测试结果表明: 桩端后注浆能提高钻孔桩竖向极限承载力约20%; 注浆期间, 桩侧摩阻力的重新分布使桩身轴力发生较大变化, 且桩端承受弯矩会对桩体结构造成一定破坏; 加载期间, 注浆桩的桩端部分承载力主要由桩侧摩阻力提供, 而非注浆桩的桩端部分承载力主要由端阻力提供; 在透水地层中, 桩承载力的提高依赖于桩侧摩阻力的影响, 而在不透水地层中扩大头的产生也会成为影响因素.     

Magnetism in Nonplanar Zigzag Edge Termini of Graphene Nanoribbons

Graphene nanoribbons (GNRs) and nanographenes synthesized by on-surface reactions using tailor-made molecular precursors offer an ideal playground for a study of magnetism towards nano-spintronics. Although the zigzag edge of GNRs has been known to host magnetism, the underlying metal substrates usually veil the edge-induced Kondo effect. Here, we report the on-surface synthesis of unprecedented, π-extended 7-armchair GNRs using 7-bromo-12-(10-bromoanthracen-9-yl)tetraphene as the precursor. Characterization by scanning tunneling microscopy/spectroscopy revealed unique rearrangement reactions leading to pentagon- or pentagon/heptagon-incorporated, nonplanar zigzag termini, which demonstrated Kondo resonances even on bare Au(111). Density functional theory calculations indicate that the nonplanar structure significantly reduces the interaction between the zigzag terminus and the Au(111) surface, leading to a recovery of the spin localization of the zigzag edge. Such a distortion of planar GNR structures offers a degree of freedom to control the magnetism on metal substrates.     

Circumcoronenes

Circumcoronene, a hexagonal graphene fragment with six zigzag edges, has been the focus of theoretical studies for many years, but its synthesis in solution has remained a challenge. In this study, we present a facile method for synthesizing three derivatives of circumcoronene using Brønsted/Lewis acid-mediated cyclization of vinyl ether or alkyne. Their structures were confirmed through X-ray crystallographic analysis. Bond length analysis, NMR measurement, and theoretical calculations showed that circumcoronene mostly follows Clar's bonding model and exhibits dominant local aromaticity. Its absorption and emission spectra are similar to those of the smaller hexagonal coronene due to its six-fold symmetry.