Synthesis of carbon nanocapsules containing Fe, Ni or Co by arc discharge in aqueous solution

A simple, inexpensive and one-step synthesis method of metal-containing carbon nanocapsules using an arc discharge in aqueous solution is reported. It was found that Ni, Co and Fe nanoparticles could be in situ encapsulated in carbon shells when the arc was performed respectively in aqueous solutions of NiSO₄, CoSO₄ and FeSO₄. Transmission electron microscopy, energy dispersive X-ray spectroscopy and electron diffraction patterns of selected areas were used to determine the crystalline phase of the metal cores. To explain the formation mechanism of metal-containing carbon nanocapsules, a model of discharge in solution is proposed. This result presents a simply controllable way to synthesize metal-containing carbon nanocapsules.     

Charge transfer effects in acid treated single-wall carbon nanotubes

Single-wall carbon nanotubes (SWNTs) prepared by the arc discharge method were oxidized using nitric acid. The samples were analyzed by using Raman scattering and Fourier transformed infrared spectroscopy (FTIR). The FTIR results indicate the presence of -COOH acid groups in the treated samples. The up shifts observed in the radial breathing mode frequencies suggest that SWNTs behave as donors after the acid treatment, with charge transfer occurring from the nanotubes to the -COOH groups. Ab initio calculations of SWNTs interacting with -COOH acid groups support the charge transfer process from the nanotubes to the carboxyl groups.     

A data porting tool for coupling models with different discretization needs

The presented work is part of a larger research program dealing with developing tools for coupling biogeochemical models in contaminated landscapes. The specific objective of this article is to provide researchers with a data porting tool to build hexagonal raster using information from a rectangular raster data (e.g. GIS format). This tool involves a computational algorithm and an open source software (written in C). The method of extending the reticulated functions defined on 2D networks is an essential key of this algorithm and can also be used for other purposes than data porting. The algorithm allows one to build the hexagonal raster with a cell size independent from the geometry of the rectangular raster. The extended function is a bi-cubic spline which can exactly reconstruct polynomials up to degree three in each variable. We validate the method by analyzing errors in some theoretical case studies followed by other studies with real terrain elevation data. We also introduce and briefly present an iterative water routing method and use it for validation on a case with concrete terrain data.     

LBMBS： A Load-Balanced Moveable Bubble Scheme for Tori Interconnection Networks

Moveable bubble flow control is an efficient technique to avoid deadlock for torus networks. However, it does not take into consideration the load balance feature. Therefore, this leads to inefficient resources utilization. Moreover, packets may be discarded due to the congestion of a network area. On the other hand, there are other algorithms that consider load balancing such as rHALB （r hop adaptive load-balanced）routing technique. Nonetheless, rHALB detects deadlock using the timeout threshold. This concept of deadlock detection may give incorrect responses in case the traffic is high. Therefore, packets are dropped although there is no deadlock. At the end, this affects the whole performance of the network. This paper proposes a new routing algorithm for tori interconnection networks, namely, the LBMBS （load-balanced moveable bubble scheme）. LBMBS integrates both concepts of moveable bubble and rHALB in order to provide at the end a load-balanced efficient deadlock-free algorithm. The protocol details are given and compared against other routing algorithms in the literature.     

基于贪婪路由协议的动态单/多链路故障恢复策略

针对现有的贪婪方法不能有效处理拓扑结构中链路故障的问题,提出单链路故障和多链路故障本地化恢复策略。首先,通过利用克莱因伯格的贪婪嵌入给出单链路故障恢复策略;然后,将其扩展到多链路故障的情况;最后,在基于Python/C++的仿真环境下对提出的技术进行评估。实验结果表明,该技术仅需要非常有限的资源,且造成的路由质量损耗也有限,可以实现快速切换,可依网络生成树中链路数目扩展。该技术的可扩展性、简单性和低开销使其适合于大型网络。     

网络边布局技术研究综述

网络边布局技术是网络可视化研究的重要内容,良好的边布局能够有效地展示网络的整体结构并从中揭示出某些隐含的信息模式.为了全面地总结和分析现有网络边布局技术,首先归纳了网络边布局的主要任务,回顾了指导网络边布局的美学标准.然后将网络边布局技术归纳为3类:边路由技术、边融合技术和边集束技术,分别阐述了各类技术中典型布局方法的主要原理和特征,并重点对边集束技术进行了分类分析.最后总结了目前研究中还存在的一些问题,展望了网络边布局技术的发展前景和面临的挑战,以期为相关领域的研究者提供有益参考.     

求解整合资源条件下的运输调度问题

针对传统的物流运输调度问题(Vehicle Routing Problem,VRP)中车辆之间不协作会造成资源浪费的情况,提出整合资源条件下的运输调度问题(Vehicle Routing Problem with Integration of resources,VRPIR),建立了相应的数学模型。由于混沌具有良好的遍历性,而粒子群优化算法(Particle Swarm Optimization,PSO)具有概念简单,参数少,容易实现等优点,将混沌优化方法引入到粒子群优化算法中,应用混沌粒子群优化算法(Chaos Particle Swarm Algorithm,CPSO)求解VRPIR和VRP,并用CPSO和PSO分别求解VRPIR,实验结果证明该算法优于粒子群优化算法,也证明了提出的VRPIR模型优于VRP,能节省资源,且最小化成本。     

一种车载自组织网络路况信息的数据信任模型

动态寻路是解决城市交通拥堵的重要手段。在动态寻路中,一些车辆产生和转发路况信息,使其他车辆能够避开拥堵路段。但一般车载自组织网络寻路算法缺乏验证路况信息的真实性的措施,导致恶意车辆能轻易篡改路况信息,误导其他车辆选择错误路线。提出了一种路况信息鉴别模型,该模型将基于数据的信任模型应用到路况信息真伪的鉴别中,并在一般投票算法的基础上利用D-S理论增加不确定情况下的鲁棒性。仿真实验表明,该算法在不增加额外信息交互的前提下,有效规避了恶意伪造信息,改进了车辆的行程时间。     

基于免疫原理的多拓扑路由生成算法

针对现有多拓扑路由生成算法存在存储资源利用不合理、多故障恢复能力无法有效适应网络环境等问题,提出了一种结合生物免疫原理的多拓扑路由生成算法。该算法以适应网络环境中常见的多故障为目标,根据免疫原理中抗原与抗体决定基无须完全吻合而只需关键部位相匹配的机制,将子拓扑生成看作免疫原理中的抗体产生,增强了多故障情况下的网络抗毁性,同时引入人工免疫算法来解决算法中的寻优问题。实验结果表明,该方法提高了网络在多故障环境下的抗毁性。     

基于最小巡游概率的网络空洞平衡唤醒算法

在网络移动Agent(MA)模式下环形路由设计中,由于网络数据包传输冲突产生空洞,需要设计空洞平衡唤醒算法,以平衡网络能量,延长网络寿命。传统方法采用自适应学习粒子群算法,构建C/S模式下的空洞平衡唤醒算法,由于网络能耗不均衡也将容易使网络产生信息空洞的孤岛节点,性能不好。提出一种基于最小巡游概率的移动Agent的能量平衡环形路由信息空洞唤醒算法,建立最小跳数链路与梯度环,提供MA休眠和唤醒所需能量,进行MA迁移与数据回传,进行最小跳数链路路由算法设计,构建最小巡游概率判别准则与整体网络拓扑结构,实现网络信息空洞平衡唤醒算法的改进。仿真结果表明,该算法能数据包跳数构建网络拓扑,有效抑制了数据包在同一梯度内重传现象,通过最小概率巡游,有效减少因节点死亡而产生网络空洞的概率,有效克服网络能耗不均衡也产生信息空洞的孤岛节点,sink节点会相继收到由内环到外环各层MA所回传的融合数据,有效延长网络使用寿命,提高系统稳定性。