PBB/VPLS双栈技术及其效率分析

PBB技术和VPLS技术是城域以太网技术发展的两个方向,PBB/VPLS双栈技术通过PBB与VPLS报文之间的互相转换实现了网络融合。文章从VPN中主机之间互相学习MAC地址的角度研究了PBB/VPLS双栈网络的效率;通过理论上的分析计算,得出了当所有主机获取其他主机MAC地址之后ARP报文被公网设备转发的次数和;对组网方式进行了研究,旨在减少公网设备转发ARP报文的次数,提升双栈网络的效率。     

电信级以太网中PBT技术与应用研究

电信级以太网是一种新兴的传输汇聚层解决方案，同时是目前技术研究的热点。在多种电信级以太网的实现技术中，PBT（Provider Backbone--Transport）技术得到众多厂商和运营商的关注。文章主要对PBT的网络结构、解决方案、应用及其特点进行了探讨。     

Mechanism and kinetics of reductive dehalogenation of PBB (polybrominated biphenyl) in the sonolytic and ketyl radical system

The kinetics and mechanism of reductive destruction of aqueous polybrominated biphenyl (PBB) were studied. Complete degradation was achieved within 30 min of ultrasound-assisted chemical process (UACP), which involved sonication, ketyl radical and its anion, and metal catalyst (ferrous ion). Reductive dehalogenation of PBB is a first-order reaction between PBB concentration and UACP reaction time. The kinetic condition of PBB degradation was optimized in terms of temperature, dosage of radical initiator, and metal catalyst. Mechanism of reductive debromination was also proposed to explain the function of ketyl and aryl radicals on the debromination of bromobiphenyl. Two kinetic models were studied to elucidate the debromination mechanism pathway. Laboratory observed data were found to fit model predicted values obtained from equilibrium and differential equations.     

The use of vegetation to remediate soil freshly contaminated by recalcitrant contaminants

The use of vegetation to remediate soil contaminated by recalcitrant hydrocarbons was tested under field conditions. Specifically, an evaluation was made of the effectiveness of deep rooting grasses, Johnsongrass and Canadian wild rye in the dissipation of TNT and PBB's in the soils freshly contaminated to an initial concentration of 10.17+/-1.35 for TNT and 9.87+/-1.23 mg/kg for PBB. The experiment used 72 (1.5m long and 0.1m diameter) column lysimeters with four treatments: Johnsongrass; wild rye grass; a rotation of Johnsongrass and wild rye grass; and unplanted fallow conditions. In the laboratory, immunoassay test procedures determined the TNT and PBB concentrations in the soil, leachate, herbage and root samples. The root characteristics such as total root length, rooting density, and root surface area were quantified to a depth of 1.5m. Changes in microbial biomass were assessed for both rhizosphere soil and the bulk soil during the 2-year study. The largest and most rapid loss in soil chemical concentration was for TNT, which decreased to less than 250 microg/kg, the detection limit, by 93 days after germination. The PBB was at or near the detection limit of 500 microg/kg by 185 days after germination. There was no perceptible difference in contaminant concentration in the soil between the vegetation treatments and/or with depth.     

Monitoring multicomponent quality traits in tomato juice using portable mid-infrared (MIR) spectroscopy and multivariate analysis

In this study, a novel portable infrared spectrometer was evaluated for rapid and simultaneous determination of glucose, fructose, total reducing sugars, soluble solids (°Brix), serum viscosity, Bostwick consistency, predicted paste Bostwick value and pH. A total of 350 hot-break juices from two consecutive years (2013 and 2014) including 66 different varieties grown in 6 counties of California, USA, were used in this study. Duplicate spectra for each tomato juice were collected using the transmission accessory of the portable infrared spectrometer at 50 μm fixed path length. Samples were randomly divided into calibration (n = 280) and external validation (n = 70) sets and partial least squares (PLS) regression was used to develop calibration models to predict all the variables (quality traits) in the validation samples based on the tomato juice spectral data (r_pred > 0.82). Overall, our validated chemometric models allowed rapidly (∼2 min) predicting all the quality traits in tomato juice samples with no sample preparation.     

PBT——一种经济可行的IP城域网关键技术

介绍了PBT技术的发展现状,阐述了基本工作机制、可扩展性、可靠性、QoS保证等技术原理,指出了采用PBT技术可能存在的风险并展望了其未来发展.     

以太网VPN技术在云数据中心互联应用的研究

对当前VPLS中存在的问题和新出现的以太网VPN需求进行概述,介绍并分析IETF最新提出的E-VPN和PBB E-VPN这两种以太网VPN的技术特征,结合正在兴起的云数据中心互联的实际应用需求,探讨以太网VPN技术在云数据中心的互联组网应用.     

支持PBB功能的扩展VPLS技术

介绍了基于MPLS的以太网技术VPLS和PBB技术．分析了VPLS的扩展性因素及层次化的VPLS,详细介绍了支持PBB功能的扩展VPLS技术。     

硬盘数据维护技术的探讨

针对目前硬盘使用中存在的若干问题，本文研究了ＤＯＳ有关数据信息存储的原理，分析了产生问题的原因，并从数据维护的角度提出了解决问题的技术和方法．     

城域网络发展趋势探讨

分组化和觅带化是下一代城域网络发展的趋势,但是向IP城域网络发展过程中,时分复用（TDM）和IP业务将长期共存。分组传送网（PTN）是兼顾TDM业务与IP化的发展方向而产生的产物,作为PTN技术的两种典型代表,传送／多协议标签交换（TMPLS）和运营商骨干桥接／运营商骨干传输（PBB／PBT）实现了分组交换,能够支持端到端链接、监控和快速的保护倒换,此外还实现了控制和传送的分离,是城域网络的发展方向之一。