Carbon corrosion mechanism on nitrogen-doped carbon support — A density functional theory study

In this work, density functional theory (DFT) calculations were used to investigate the mechanism of carbon corrosion on nitrogen-doped carbon support. Free energy diagrams were generated based on three proposed reaction pathways to evaluate corrosion mechanisms. The most energetically preferred mechanism on nitrogen-doped carbon was determined. The results show that the step of water dissociation to form ^#OH was the rate-determining step for gra-G-1N (graphene doped with graphitic N) and pyrr-G-1N (graphene doped with pyrrolic N). As for graphene doped with pyridinic N, the step of C^#OC^#O formation was critical. It was found that the control of nitrogen concentration was necessary for precisely designing optimized carbon materials. Abundance of nitrogen moieties aggravated the carbon corrosion. When the high potential was applied, specific types of graphitic N and pyridinic N were found to be favorable carbon modifications to improve carbon corrosion resistance. Moreover, the solvent effect was also investigated. The results provide theoretical insights and design guidelines to improve corrosion resistance in carbon support through material modification by inhibiting the adsorption of surface oxides (OH, O, and OOH).     

Elucidation of colour development and microstructural characteristics of Allium sativum fumigated with acetic acid

It has been well known that the greening of Allium sativum cloves could be formed after immersed in acetic acid solution. Nonetheless, no investigation was reported on colour development of A. sativum in response to acetic acid vapour until now. In this study, the brief exposure of A. sativum to acetic acid vapour (200–400 ppm) was combined with controlled atmosphere (5%, 20% and 80% CO₂) packaging storage to break cell membrane and green garlic. The garlic bulbs were fumigated with acetic acid before controlled CO₂ atmosphere packaging for 25 days at 4 °C. Fumigation with 200 ppm acetic acid followed by high CO₂ atmosphere packaging (80% CO₂) facilitated the garlic greening. It was also verified that γ‐glutamyl transpeptidase was involved in garlic greening in present study, and the compromise of glacial acetic acid vapour fumigation and CO₂ gas atmosphere in package stored at low temperature could result in garlic greening as well.     

ATM网VBR编码会议电视业务模型的研究

文章研究了ATM网中VBR编码的会议电视业务的模型，提出一阶自回归、瑞利分布残差而不是高斯分布的AR序列模型──RAR（1），实验表明，该模型能产生足够多的大信元帧数，这对于研究信元丢失率特性具有至关重要的影响，而且简单实用。此外，RAR（1）模型在较少（16个）和较多（128个）VBR信源统计复用时，能很好地拟合实际的会议电视业务的统计数据。     

桌域网及其新技术的研究

桌域网是一种适合于多媒体业务需要的小型ATM网 ,是对传统计算机网络的体系结构的一种补充。本文介绍了设计桌域网的基本策略 ,讨论了它的设计目标和特性 ,给出了桌域网的体系结构、网络接入设备及其性能 ,最后提出研究桌域网的几点建议。     

横观各向同性土介质与结构物共同作用的有限元与边界元耦合分析

本文采用有限元与边界元耦合方法对上与结构物进行共同作用的分析．其中上部结构采用有限元子结构法，地基上考虑为横观各向同性特性，应用边界元法，通过基础界面上位移连续、面力平衡的条件进行耦合分析．编制了相应的计算程序，对某高层空间剪力培与地基的共同作用进行了计算，与有限元法和实测结果进行了对比分析，得到了满意的结果．说明：有限元和边界元的耦合方法能充分发挥两者的优越性，不失为共同作用分析的一种有效途径．     

网络流量监控系统的设计与实现

在网络技术高速发展的同时,互联网的网络安全问题已经成为广泛关注的焦点,恶意攻击、病毒感染、非法访问都是影响网络运行的主要问题,在目前网络安全体系中,针对流量的监控便是其中一种有效分析网络状况的办法,它将从流量的角度来监控网络是否存在异常情况。     

永定河水资源现状与管理探讨

结合北京市水资源现状和特点,分析北京市境内永定河流域水资源情况、降水特点;以地表水为主,从洪水调度和日常水资源调度2个方面分析永定河水资源管理现状、管理权限、管理流程和存在问题,提出南水北调进京后,永定河水资源管理所面临新的挑战,同时需要完善永定河水资源管理制度和监测设施等,提高水资源管理和调度的科学性。     

变频机组小波分析早期故障检测系统的设计

变频机组是地空导弹武器电源系统中不可缺少的重要设备之一.为及时发现机组早期故障以保证正常战备,设计研制了基于小波分析的早期故障检测系统.证明了变频机组发生定子匝间短路时,定子电流中的3次和5次谐波会明显增大的现象,同时利用改进谐波小波提取了这两种谐波分量,并将其作为变频机组发生定子匝间短路时的故障特征分量,分别从软硬件两个方面阐述了系统的总体设计方案.某导弹旅对系统进行的实地试验结果表明,系统能够成功检测到故障特征分量,从而验证了系统的可行性.     

新型引水式电站布置方式在小天都水电站的建设实践

四川省甘孜藏族自治州康定县境内的小天都水电站 ,在优化设计中采用了气垫调压室技术和新型的“一坡到底”方式布置引水洞线的布置方式。具有技术先进、安全可靠、投资省、工期短的优点 ,为解决工程建设中地质、环境影响的两大难题铺平了道路