四边形板开孔动力学优化设计研究

四边形板内开孔后,其原有的力学性能要发生改变。开孔的形状、位置和转动等因素都会对其性能产生影响。采用超椭圆方程对开孔边界进行数学描述。通过遗传算法对开孔进行优化设计,使开孔板的动力特性达到最优。通过一些典型算例验证所用方法的可行性,以及优化结果的准确性。计算结果表明对开孔进行优化设计,可以明显改善板的动力性能。     

基于特征约束的四边形网格划分算法

鉴于有限元分析的特殊需要，提出了一种基于特征约束的四边形网格划分方法。将特征约束分为点约束和线约束，分别采用不同的方法进行处理，然后利用改进的铺砌法进行网格划分。从而生成质量良好的四边形网格。     

单晶多孔ZnO制备及对室内空气污染物的气敏性能的研究

通过使用对液相法合成的前驱体进行煅烧的方法成功的制备了具有单晶多孔结构的Zn O纳米片。通过X射线衍射仪(XRD)、环境扫描电子显微镜(FESEM)、高分辨透射电子显微镜(TEM)对单晶多孔Zn O纳米片进行了结构以及形貌的表征和分析。以其为敏感膜,制作气体传感器,对室内空气污染物,包括苯和甲醛,进行检测。结果显示单晶多孔Zn O纳米片对苯和甲醛都有着良好的响应,且响应和恢复时间都非常迅速。对敏感机理以及材料的结构对响应时间的影响也进行了较深入的探讨。     

A 9-node co-rotational quadrilateral shell element

A new 9-node co-rotational curved quadrilateral shell element formulation is presented in this paper. Different from other existing co-rotational element formulations: (1) Additive rotational nodal variables are utilized in the present formulation, they are two well-chosen components of the mid-surface normal vector at each node, and are additive in an incremental solution procedure; (2) the internal force vector and the element tangent stiffness matrix are respectively the first derivative and the second derivative of the element strain energy with respect to the nodal variables, furthermore, all nodal variables are commutative in calculating the second derivatives, resulting in symmetric element tangent stiffness matrices in the local and global coordinate systems; (3) the element tangent stiffness matrix is updated using the total values of the nodal variables in an incremental solution procedure, making it advantageous for solving dynamic problems. Finally, several examples are solved to verify the reliability and computational efficiency of the proposed element formulation.     

Facile tuning of superhydrophobic states with Ag nanoplates

GaAs wafers have been decorated with Ag nanoplates through direct galvanic reaction between aqueous AgNO₃ solutions and GaAs, resulting in Ag nanoplate/GaAs composite surfaces with varying hydrophobocity after the Ag nanoplates are coated with self-assembled monolayers of alkyl thiol molecules. By carefully controlling the reaction conditions, such as growth time and concentration of the AgNO₃ solution, the size, thickness, and surface roughness of the individual Ag nanoplates can be tuned in order to produce different topographic structures and roughness of the composite surfaces, which in turn infl uences the hydrophobicity of the surfaces. The as-synthesized composite surfaces have been found to exhibit various levels of hydrophobicity and different wetting states such as the Wenzel wetting state, Cassie impregnating wetting state, and Cassie nonwetting state. The relationship between surface structure and hydrophobic state is also discussed. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users. This article is published with open access at Springerlink.com     

Size- and shape-controlled conversion of tungstate-based inorganic-organic hybrid belts to WO3 nanoplates with high specific surface areas

Two-dimensional monoclinic WO(3) nanoplates with high specific surface areas are synthesized through a novel conversion process using tungstate-based inorganic-organic hybrid micro/nanobelts as precursors. The process developed involves a topochemical transformation of tungstate-based inorganic-organic hybrid belts into WO(3) nanoplates via an intermediate product of H(2)WO(4) nanoplates, utilizing the similarity of the W-O octahedral layers in both H(2)WO(4) and WO(3). The as-obtained WO(3) nanoplates show a single-crystalline nanostructure with the smallest side along the [001] direction. The WO(3) nanoplates are 200-500 nm x 200-500 nm x 10-30 nm in size, and their specific surface areas are up to 180 m(2) g(-1). Photocatalytic measurements of visible-light-driven oxidation of water for O(2) generation in the presence of Ag(+) ions indicate that the activity of the as-obtained WO(3) nanoplates is one order of magnitude higher than that of commercially available WO(3) powders.     

Dimension-controlled synthesis of CdS nanocrystals: from 0D quantum dots to 2D nanoplates

The dimension-controlled synthesis of CdS nanocrystals in the strong quantum confinement regime is reported. Zero-, one-, and two-dimensional CdS nanocrystals are selectively synthesized via low-temperature reactions using alkylamines as surface-capping ligands. The shape of the nanocrystals is controlled systematically by using different amines and reaction conditions. The 2D nanoplates have a uniform thickness as low as 1.2 nm. Furthermore, their optical absorption and emission spectra show very narrow peaks indicating extremely uniform thickness. It is demonstrated that 2D nanoplates are generated by 2D assembly of CdS magic-sized clusters formed at the nucleation stage, and subsequent attachment of the clusters. The stability of magic-sized clusters in amine solvent strongly influences the final shapes of the nanocrystals. The thickness of the nanoplates increases in a stepwise manner while retaining their uniformity, similar to the growth behavior of inorganic clusters. The 2D CdS nanoplates are a new type of quantum well with novel nanoscale properties in the strong quantum confinement regime.