Active Sites Engineering toward Superior Carbon‐Based Oxygen Reduction Catalysts via Confinement Pyrolysis

Developing efficient and low‐cost defective carbon‐based catalysts for the oxygen reduction reaction (ORR) is essential to metal–air batteries and fuel cells. Active sites engineering toward these catalysts is highly desirable but challenging to realize boosted catalytic performance. Herein, a sandwich‐like confinement route to achieve the controllable regulation of active sites for carbon‐based catalysts is reported. In particular, three distinct catalysts including metal‐free N‐doped carbon (NC), single Co atoms dispersed NC (Co–N–C), and Co nanoparticles‐contained Co–N–C (Co/Co–N–C) are controllably realized and clearly identified by synchrotron radiation‐based X‐ray spectroscopy. Electrochemical measurements suggest that the Co/Co–N–C catalyst delivers optimized ORR performance due to the rich Co–N_x active sites and their synergistic effect with metallic Co nanoparticles. This work provides deep insight for rationally designing efficient ORR catalyst based on active sites engineering.     

无线局域网安全问题及解决方案

随着无线局域网（WLAN）的普及,其安全问题越来越受到人们的关注。现有的无线局域网基础设施都支持IEEE802.11或802.11b标准,但这些标准下所定义的加密和认证协议WEP（Wired Equivalent Privacy）协议存在着很多的安全漏洞。首先分析了WEP协议面临的各种安全机制和存在风险。提出了两种弥补漏洞提高WLAN安全性的方案：一种是临时的改进方案,另一种是为了架设新的WLAN基础设施而提出的高级安全方案。最后,提出了实际无线组网安全的几点主观建议。     

基于ARM-Linux的矿井安全监控系统设计与实现

以当前矿井安全的现状与需求为出发点,对基于ARM-Linux的矿井安全监测控制系统进行深入研究,提出基于嵌入式技术的矿井安全监控系统的总体设计方案;通过构建该平台的模型和分析嵌入式终端的体系结构,阐述了在以Linux操作系统和ARMS3C2410X处理器为核心的终端软硬件基础上,系统各主要功能模块的实现;在所构建的矿井安全监控硬件平台上,应用HTTP协议,成功实现了远程终端对井上监控终端的控制与访问.     

校园网安全接入身份认证系统设计与实现

网络接入认证是网络安全管理的一个重点。本文主要探讨了网络接入认证技术中较为流行的802．1X技术,根据我校的网络基础及管理需要,提出了应用于实际的WebPortal和802．1X相结合的技术方案,较好地解决了网络管理难题。     

容错控制系统的一类新型阵列码技术

随着现代化生产的不断发展,控制系统变得日渐复杂,出现各类故障的可能性也随之增大.为了解决控制系统复杂化引起系统安全性减低的问题,人们将编码技术作为一种软件冗余技术应用于控制系统,由于控制系统具有强实时性的要求,因此阵列码技术成为主流技术.阵列码技术虽然具有纠错时间短的优点,但是纠错能力有限,一般只能纠正一到两个磁盘错误.针对上述不足提出一种能够在三个磁盘同时发生错误的条件下有效恢复数据的新型阵列码-扩展X码,给出编译码算法,并将其应用于火箭控制系统的容错.     

HCS12X单片机的SD卡FAT文件系统读写设计

基于HCS12X单片机SPI模块读取Micro SD卡与SD卡,并解析SD卡上FAT文件系统以实现文件的读取与写入。测试证明,系统对FAT文件系统的读取稳定,误差小,速度较快。使用HCS12X类单片机对SD卡进行读取,在汽车智能设计和单片机调试方面有较高的应用价值。     

无线局域网802.11x技术

在这个＂网络就是计算机＂的时代,伴随着有线网络的广泛应用,以快捷高效,组网灵活为优势的无线网络技术正在飞速发展。无线局域网是计算机网络与无线通信技术相结合的产物。本文论述了无线局域网的概念、特点,以及无线局域网的协议标准和安全技术,重点论述了无线局域网的最新协议IEEE802.11n的适用场合及所采用的最新技术MIMO技术。     

Assisting designer using feature modeling for lifecycle

This paper presents a product dynamic model and design for X solution (DFX) developed in C++ with the OpenCASCADE geometric kernel, allowing the designer not only to get feedback on the viability of his design choices but also to collect data for process and task planning, maintenance and end-of-life strategy planning. The implemented method evaluates automatically both the efficiency factors and the incompatibilities between development characteristics in order to optimize the design of the product for multiple domains. The framework of this DFX solution, based on the product data structure, consists of imposing integration constraints concerning the development process during the entire design product process. In this paper, simple assemblies are used as brief examples to demonstrate the application of the proposed integrated design solution, its effectiveness to improve the design for X and collecting useful data for entire lifecycle duration. The method developed has been formalized with the NIAM model.     

使用ActiveX Internet控件建立Internet应用程序

使用Ａｃｔｉｖｅ Ｘ Ｉｎｔｅｒｎｅｔ控制组件来建立Ｉｎｔｅｒｎｅｔ应用程序是一条简单高效的途径。本文简要介绍了ＡｃｔｉｖｅＸ Ｉｎｔｅｒｎｅｔ控件的易用性,说明了它们的一般使用方法,并结合ＶＢ给出了一个实例。