Tracking topological entity changes in 3D collaborative modeling systems

One of the key problems in collaborative geometric modeling systems is topological entity correspondence when topological structure of geometry models on collaborative sites changes.In this article,we propose a solution for tracking topological entity alterations in 3D collaborative modeling environment.We firstly make a thorough analysis and detailed categorization on the alteration properties and causations for each type of topological entity,namely topological face and topological edge.Based on collaborative topological entity naming mechanism,a data structure called TEST (Topological Entity Structure Tree) is introduced to track the changing history and current state of each topological entity,to embody the relationship among topological entities.Rules and algorithms are presented for identification of topological entities referenced by operations for correct execution and model consistency.The algorithm has been verified within the prototype we have implemented with ACIS.     

理实一体化在《精细化工工艺学》课程教学中的应用与思考

在《精细化工工艺学》课程教学中运用理实一体化教学模式，采用演示法，参观法，实训法，讨论法等多种教学方法，可提高学生的实践操作技能、激发学生的学习兴趣，增强学生分析问题、解决问题的能力，提高教学效果。同时，在实施理实一体化教学过程中，需要对原专业课程整合、优选教学项目、加强“双师型”教师队伍建设、建设与之相匹配的教学实施、制定科学合理的评价体系。     

实时协同工作系统中操作转换算法综述

首先分析了实时协同工作系统中的事件关系,讨论了一致性模型及其收敛问题,然后以典型实时协同工作系统中操作转换算法的研究进展为线索,将算法中最核心的调度函数剥离出来,进行了详细的分析 .对意图维护问题进行了解析,将其归结为在立即模式下对并发问题的处理,得出了意图维护问题在算法层面的准则 .最后对基本转换函数和典型转换算法进行了归纳和总结,并对进一步研究方向进行了探讨 .     

异构CAD数据交换中样条草图的处理方法

针对现有异构CAD系统间的产品数据交换方法对样条草图处理不足问题,提出了支持样条草图参数化交换的草图数据交换构架。将草图数据交换分为简单参数草图数据交换和复杂参数草图数据交换。重点分析了复杂参数草图数据交换问题,通过引入Hausdorff距离作为适应度评价方法,构建了基于粒子群优化求解的样条草图参数化交换算法,利用曲率自适应学习因子来避免局部最优解,使得不同曲率区域的参数点位置合理分布。所提方法在异构CAD系统间进行了实验测试,结果证明了本方法的有效性。     

基于遗传算法和模糊C均值聚类的WSN分簇路由算法

针对无线传感器网络（WSN）的节点能量有限、生命周期短、吞吐量低等问题，提出一种基于遗传算法（GA）和模糊C均值（FCM）聚类的WSN分簇路由算法GAFCMCR，采取"集中分簇，分布簇头选举"的方式。网络初始化时基站采用由GA优化的FCM聚类算法形成网络分簇。第一轮簇头由距簇中心最近的节点担任；从第二轮开始，簇头的选举由上一轮的簇头负责，选举过程综合考虑候选节点的剩余能量、与基站的距离、与簇内其他节点的平均距离三个因子，并根据网络状态实时调整三个因子的权重。在数据传输阶段，将轮询机制引入簇内通信。仿真结果表明，相同网络环境下，与LEACH算法和基于K-Means的均匀分簇路由（KUCR）算法相比，GAFCMCR将网络生命周期延长了105%和20%。GAFCMCR成簇效果良好，具有良好的能量均衡性和更高的吞吐量。     

Preparation of zirconium phenylphosphonate films with different crystallite orientations on polystyrene substrates by in situ hydrothermal crystallization

Zirconium phenylphosphonate (ZrPP) films with different crystallite orientations have been fabricated on unmodified and surface-sulfonated polystyrene (PS) substrates by an in situ hydrothermal crystallization method. On the unmodified PS substrate, a monolayer film with the hexagonal ab planes of the ZrPP crystallites parallel to the PS can be obtained by restricting the crystallization time. After a longer crystallization time, the ZrPP films adopt a bilayer arrangement, with the ab planes of the ZrPP crystallites in the lower layer being parallel to the substrate, and the ab planes of the ZrPP crystallites in the upper layer being perpendicular to the substrate. On the surface-sulfonated PS, however, the ZrPP crystallites form a monolayer film with their ab planes perpendicular to the substrate irrespective of the crystallization time. We suggest that the different interactions between the ZrPP crystallites and the two substrates, namely the π-π interactions between the phenyl groups in the ZrPP surface and those in the unmodified PS substrate, and the coordinate interactions between the lone pairs of electrons on oxygen atoms in the sulfonate groups on the sulfonated PS and vacant coordination sites on Zr atoms on the edges of ZrPP crystallites, are responsible for the different morphologies of the monolayer films on the unmodified and sulfonated substrates. Two distinct growth mechanisms are proposed which can satisfactorily account for the different crystallite orientations in the two ZrPP films.     

Scalable preparation of alginate templated-layered double hydroxide mesoporous composites with enhanced surface areas and surface acidities

Layered double hydroxides (LDHs), also known as hydrotalcite-like layered clays, have previously been investigated as a potential solid alkaline catalyst. A necessary calcinations/rehydration procedure, however, is utilized to enhance surface area and catalytic activity of LDHs involved. Here we report on a scalable preparation of sodium alginate-templated MgAI-LDH (LDH/SA) mesoporous composites with high surface area and surface acidity. The powdery LDH/SA mesoporous composites are prepared using alginate as template by a scalable method of separate nucleation and aging steps (SNAS). Comparison with the pristine MgAl-LDH shows that the obtained LDH/SA composites exhibit the greatly enhanced surface area and surface activity of surface acid sites at the elevated high temperatures which have scarcely been reported previously. Our results may allow designing a variety of mesoporous LDH-containing composites with potential applications in specific catalysis and purification processes.     

Dye-sensitized solar cells based on multilayered ultrafine TiO2 nanowire photoanodes

A low-temperature hydrothermal method was used to synthesize ultrafine TiO₂ nanowires with the diameter of 4–6 nm. The ultrafine nanowires tend to gather together, forming nanowire bundles. The length of the nanowires is about 1–4 μm, depending on the growth time. Multilayered TiO₂ nanowires with the height more than 10 μm have been synthesized by a multi-step growth process. Furthermore, the dye-sensitized solar cells (DSSCs) are assembled using single-layered, double-layered and triple-layered TiO₂ nanowires as photoanode respectively. The DSSC based on triple-layered TiO₂ nanowires shows the highest power conversion efficiency of 3.96 % among the prepared samples. The relatively high energy conversion efficiency is attributed to the large surface area, which enhances the absorption of dye molecules.     

外装式钢包透气砖的研制与应用

介绍了武钢-炼钢厂外装式钢包透气砖的研制与应用，实践证明该从气系统安全性高、可靠性好、寿命长、操作简单。