添加剂硼对纯铁粉末触媒合成金刚石的影响

本义研究了添加剂硼对纯铁粉末触媒合成金刚石的影响。实验中将不同比例的无定形硼粉直接添加到石墨-纯铁粉末体系中并均匀混合，以此方式，将硼掺杂到高温高压合成的金刚石单晶中。实验结果表明，随硼添加比例的不同，合成金刚石的最低压力点也不同；同时，通过不同添加比例的硼合成出金刚石的颜色，可得知该方法对提高金刚石内硼含醚的有效性。实验还发现，当硼添加比例一定时，合成温度对合成金刚石的特性产生了一系列的影响。     

Hydrogen sorption properties of Mg-20wt.%Fe 23 Y8 composite prepared by reactive mechanical alloying

Mg-20wt.% Fe23Y8 composite was successfully prepared by reactive mechanical alloying (RMA). X-ray diffraction (XRD) measurement shows that the main phases of composite are MgH2 and Mg2FeH6. The composite exhibits excellent hydrogen abs/desorption properties and can absorb 4.36wt.% and 5.72wt.% hydrogen at 473 and 573 K in 10 min under 3.0 Mpa hydrogen pressure, respectively. The composite can desorb 5.27wt.% hydrogen at 573 K in 30 min under 0.02 Mpa hydrogen pressure. Compared with the pure MgH2, the hydrogen desorption temperature of Mg-20wt.% Fe23Y8 composite is decreased about 40 ℃. It is supposed that both the catalyst effect of Fe-Y distributed in Mg substrate and the crystal defects play the main role in improving hydrogen sorption properties of Mg-20wt.% Fe23Y8 composite.     

IXP425和DM642的会议电视多点控制单元硬件设计

介绍了采用IXP425作为核心主控单元和3片DM642作为核心数据处理单元的会议电视多点控制单元的硬件设计原理和实现方法。主控制器IXP425模块完成网络发送/接收、数据调度、PCI控制等功能。数据处理DM642模块完成音/视频混合与切换等功能。IXP425和DM642之间采用PCI总线连接,各模块之间数据传输速度快,提高了数据处理效率。     

Trajectory linearization control for a miniature unmanned helicopter

Trajectory linearization control (TLC) approach is applied to design a nonlinear trajectory tracking controller for a miniature unmanned helicopter. The controller is based on nonlinear model derived from Newton-Euler equations, with collective and cyclic pitches being regarded as actual controls. Via model simplifications, the nonlinear helicopter model can be transformed into a cascaded form including four subsystems. Corresponding with the simplified cascaded structure, the proposed controller is constructed by synthesizing TLC designs for subsystems. Each of them includes designs of a pseudo-inversion and an error regulator. A summarized TLC algorithm for the unmanned helicopter is listed briefly after the detailed controller design process. Simulation results are provided to demonstrate performances of the closed-loop system.     

基于ISO9000质量管理体系的高校多媒体管理及服务系统设计

本文把高校的多媒体管理系统与ISO9000质量管理体系相结合,探讨了基于ISO9000质量管理体系的高校多媒体管理及服务系统的设计,主要包括两方面,一是把质量管理体系应用到服务教学方面,二是把质量管理体系应用到内部管理方面,而内部管理同时又是为了更好地服务教学,通过ISO9000质量管理体系二者可达到空前的统一.     

基于Web的法律咨询系统的设计与实现

针对法律案例多样化,且法律条文中通常都含有大量专业性很强的法律专用语,使得法律按照条文来分析自身面临了很大难题,本文研究了基于Web的法律信息服务平台的设计与实现,将冗杂无序的网上法律信息进行统一搜集和分类,并提供了大量案例供用户阅读,为用户提供更多有价值的法律信息.系统主要功能有:商务实务查询,相关信息查询,用户权限管理.案例及其类别管理,法律法规及其类别管理,简易论坛,案例搜索,法律法规查询,相似案例查找等.本系统的核心功能是相似案例查找和关键字搜索功能,常要利用Lucene进行切词处理.相似案例查找功能逆向运用了KNN算法的思想,在切词处理后,形成空间向量,利用空间向量计算来分析两案例的相似度,从而实现了相似案例查找.为了实现关键字搜索功能,利用Lucene实现了对数据库中的案例的全文动态索引处理,从而提高了搜索速度和搜索精度.     

IP流媒体技术在电视转播系统中的应用

概述了IP流媒体技术的特点、原理,并与其他技术方案进行了对比,重点论述了利用该技术组建电视转播系统的过程,为在类似案例情况下选择技术方案提供实践依据。     

An Efficient One-Arrow-Two-Hawks Strategy Achieves High Efficiency and Stable Batch Variance for Benzodifuran-based Polymer Solar Cells

With the development of organic solar cells (OSCs), the high-performance and stable batch variance are becoming a new challenge for designing polymer donors. To obtain high photovoltaic performance, adopting polymers with high molecular weight as donors is an ordinary strategy. However, the high molecular weight need to subtly control the reaction time and state, inevitably caused batch-to-batch variations. Herein, a strategy of steric effect is applied to benzodifuran (BDF)-based polymer by introducing different positions of Cl atom, producing two polymers PBDFCl-1 and PBDFCl-2. The more twisted side chains conformation not only achieve the control of moderate molecular weight for PBDFCl-2, but also easily form molecular stacking through adopting BDF unit and maintain sufficient polymeric crystallinity. Due to the optimized stacking mode and good blend miscibility, PBDFCl-2-based device exhibitsa more elegant power conversion efficiency (PCE) of 17.00% compared to PBDFCl-1-based device. This is the highest efficiency record for BDF-based binary OSCs. Meanwhile, the PCE device variation of the different molecular weights for PBDFCl-2 is little, indicating the reduction of the batch variation. Therefore, smartly using steric effect of Cl atom in strong crystalline BDF unit can form efficient molecular stacking regulations and realize the coordination of high-performance and stable batch variance.     

Creating Atomic Ordering in Electrocatalysis

Catalysis always proceeds in a chaotic fashion. Therefore, identifying the working principles of heterogeneous catalysts is a challenging task. Creating atomic order in heterogeneous catalysts simplifies this task and also offers new opportunities for rationally designing active sites to manipulate catalytic performance. The recent rapid advances in heterogeneous electrocatalysis have led to exciting progress in the construction of atomically ordered materials. Here, the latest progress in electrocatalysts with the periodic atomic arrangement, including intermetallic compounds with long-range order and metal atom-array catalysts with short-range order is summarized. The synthesis principles and the intriguing physical and chemical properties of these electrocatalysts are discussed. Furthermore, the compelling prospects of atomically ordered catalysts in the frontier of catalyst research are outlined.     

Tough Transient Ionic Junctions Printed with Ionic Microgels

Emerging soft ionotronics better match the human body mechanically and electrically compared to conventional rigid electronics. They hold great potential for human-machine interfaces, wearable and implantable devices, and soft machines. Among various ionotronic devices, ionic junctions play critical roles in rectifying currents as electrical p–n junctions. Existing ionic junctions, however, are limited in electrical and mechanical performance, and are difficult to fabricate and degrade. Herein, the design, fabrication, and characterization of tough transient ionic junctions fabricated via 3D ionic microgel printing is reported. The 3D printing method demonstrates excellent printability and allows one to fabricate ionic junctions of various configurations with high fidelity. By combining ionic microgels, degradable networks, and highly charged biopolymers, the ionic junctions feature high stretchability (stretch limit 27), high fracture energy (>1000 Jm⁻²), excellent electrical performance (current rectification ratio >100), and transient stability (degrade in 1 week). A variety of ionotronic devices, including ionic diodes, ionic bipolar junction transistors, ionic full-wave rectifiers, and ionic touchpads are further demonstrated. This study merges ionotronics, 3D printing, and degradable hydrogels, and will motivate the future development of high-performance transient ionotronics.