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.     

外卖配送路径多目标实时优化研究

随着外卖行业的不断发展,外卖配送的路径优化问题已引起学者们的广泛关注。但现有研究未将骑手的目标考虑在内,且未考虑动态场景下多目标如何设定权重的问题。因此,本文对外卖配送路径的多目标实时优化进行深入研究。建立多目标外卖配送路径优化模型。该模型不仅考虑订单履行时间、平台利润和骑手服务质量3个常用的目标,另外增加骑手等待时间和骑手空驶距离这两个目标,充分将外卖平台、顾客和骑手的目标综合考虑。设计动态调整权重的多目标外卖配送路径启发式算法,解决动态场景下多目标权重如何设定的问题。通过外卖配送的实时数据进行算例分析。结果表明,本文提出的算法可以有效对多目标的外卖配送问题进行实时路径优化,且订单的密集程度对骑手等待时间和订单履行时间有直接的影响。     

关于不定期多阶段决策问题的策略空间迭代法

利用图论知识,对不定期多阶段决策问题的策略空间迭代法的概念和方法,给出一种确切和完整的新的论述。     

公交线路查询系统的数据库设计

本文以公交线路查询系统为例。对数据库设计进行了研究。从不同角度考虑,设计出不同结构的数据库．可以看出数据库结构设计对数据处理操作的影响。本系统使用Visual Foxfro6作为开发工具,通过数据库表的逐步设计,实现了预定功能。     

VMware虚拟机的虚拟网络拓扑结构和配置

本文主要介绍在单机环境中.如何通过VMware软件构造虚拟网络的拓扑结构,从而可完成网络环境中的各种网络配置试验.如DHCP、DNS.NAT、Firewall等.并可熟练操作各种虚拟机操作系统.如Linux、Windows等,可进行各种类型网络应用服务器的配置试验.如Web、FTP等,同时在虚拟网络中可进行各种网络安全攻防试验.     

基于地理位置改进的动态源路由协议

本文对DSR协议进行局部改进,提出有限半径内的洪泛与半径区域间依靠最短地理位置来选择最优下一跳中转节点的机制。改进后的协议减少了路由发现过程的开销和端到端分组传输的平均时延,更适合实时业务需求。     

A novel three-tiered visualization approach for firewall rule validation

Firewall is one of the most critical elements of the current Internet, which can protect the entire network against attacks and threats. While configuring the firewalls, rule configuration has to conform to, or say be consistent with, the demands of the network security policies such that the network security would not be flawed. For the security consistency, firewall rule editing, ordering, and distribution must be done very carefully on each of the cooperative firewalls, especially in a large-scale and multifirewall-equipped network. Nevertheless, a network operator is prone to incorrectly configure the firewalls because there are typically thousands or hundreds of filtering/admission rules (i.e., rules in the Access Control List file, or ACL for short), which could be set up in a firewall; not mentioning these rules among firewalls affect mutually and can make the matter worse. Under this situation, the network operator would hardly know his/her misconfiguration until the network functions beyond the expectation. For this reason, our work is to build a visualized validation system for facilitating the check of security consistency between the rule configuration of firewalls and the demands of network security policies. To do so, the developed validation system utilizes a three-tiered visualization hierarchy along with different compound viewpoints to provide users with a complete picture of firewalls and relationships among them for error debugging and anomaly removal. In addition, in this paper, we also enumerate the source of security inconsistency while setting ACLs and make use of it as a basis of the design of our visualization model. Currently, part of the firewall configuration of our campus network has been used as our system's input to demonstrate our system's implementation.     

WSN中基于定向天线的节能寻路机制

提出无线传感器网络中基于定向天线的能量有效的路由方案。结合无线信道的特点对无线传感网中的能耗因素进行分析,得出给定源宿节点之间的距离时路径消耗总能量与中继节点数的关系。提出一个节省能量的寻路机制,在初始化阶段根据sink和邻居节点的地理信息决定能量最优的理想路径,以此为依据,结合定向天线进行能量有效的路径选择。仿真结果证明,该方案能选择一条较优路径,有效地节省能量。     

一种改进的Chord网络模型

经典的Chord模型中为维护Chord环路由信息而周期性执行的Stabilize操作产生了大量的消息转发。提出一种改进的Chord模型,通过使用优化的双向Finger表,使得只在节点加入或离开时才进行路由更新,降低了消息转发的开销,同时优化了路由定位算法。     

可证明安全的节点不相交多路径源路由协议

多路径路由实现是移动ad hoc网络可靠运行的有效保证.针对多路径路由协议的安全性分析,建立了基于UC(universally composable)框架的可证明安全路由协议的新方法.基于攻陷的网络拓扑模型,扩展了可模糊路由概念,提出了多路径可模糊路由集合概念,用于描述攻陷网络拓扑结构的移动ad hoc网络多路径路由;基于UC安全模型,提出了基于UC-RP(universally composable security framework for ad hoc networks routing protocol)框架的路由协议形式化安全定义;针对MNDP(multiple node-disjoint paths)协议存在的安全问题,提出了新的移动ad hoc网络节点不相交多路径动态源路由协议(简记为SMNDP(security multiple node-disjoint paths)协议).将基于UC-RP框架的可证明安全路由协议的新方法应用于SMNDP协议的安全分析.SMNDP协议的可证明安全性可以归约为消息认证码和签名机制的安全性.SMNDP协议实现了路由发现协议的正确性、节点身份的认证性和路由消息的完整性.