Network traffic prediction based on a new time series model

Fast and accurate methods for predicting traffic properties and trend are essential for dynamic network resource management and congestion control. With the aim of performing online and feasible prediction of network traffic, this paper proposes a novel time series model, named adaptive autoregressive (AAR). This model is built upon an adaptive memory‐shortening technique and an adaptive‐order selection method originally developed by this study. Compared to the conventional one‐step ahead prediction using traditional Box–Jenkins time series models (e.g. AR, MA, ARMA, ARIMA and ARFIMA), performance results obtained from actual Internet traffic traces have demonstrated that the proposed AAR model is able to support online prediction of dynamic network traffic with reasonable accuracy and relatively low computation complexity. Copyright © 2005 John Wiley & Sons, Ltd.     

Effects of various post-treatments on carbon nanotube films for reliable field emission

In this report, the FE characteristics of carbon nanotubes (CNTs) treated using both thermal annealing and mechanical coatings on the as-grown CNTs systematically studied. It was found that in the high temperature annealed samples, CNTs were attacked at its root during annealing due to a small amount of oxygen, and were pulled out of the substrate in places after FE measurements because of the contact resistance. However, for the mechanically coated samples both with spin on glass (SOG) and polymethyl methacrylate (PMMA), CNTs were found to be nearly intact after FE measurements and showed reliable FE characteristics over repeatable voltage scan. The reliability of CNTs during FE could be owing to the strong adhesion of CNTs to the substrate both by SOG and PMMA coatings.     

Acidogenic fermentation of blended food‐waste in combination with primary sludge for the production of volatile fatty acids

The performance of a laboratory‐scale anaerobic acidogenic fermenter fed with a mixture of blended kitchen food‐waste and primary sludge from a sewage treatment plant was investigated for the production of volatile fatty acids (VFA). The operating variables for acidogenic fermentation were kitchen food‐waste content (10 and 25 wt %), hydraulic retention time (HRT: 1, 3 and 5 days), temperature (ambient: 18 ± 2 °C, and mesophilic: 35 ± 2 °C) and pH (varied from 5.2 to 6.7). The experimental results indicated that effluent VFA concentrations and VFA production rates were higher at ambient temperature than at mesophilic conditions. The net amount of VFA with 10 wt % food‐waste increased up to 920 mg dm^?3 with an increase of HRT, but contrasting results (a decrease of 2610 mg dm^?3) were found due to the conversion of VFA into biogas in the case of 25 wt % food‐waste, which increased significantly at HRT of 3–5 days. In terms of biogas composition (CO₂ and CH₄), the organic matter was converted into CO₂ through the oxidative pathway by facultative species at low temperature while mesophilic temperature and optimum pH (6.3–7.8) played a pivotal role in increasing rate of conversion of VFA into biogas by methanogenesis. Rates of VFA production and their conversion are dependent on the food‐waste content in the mixture. Yet, the higher concentration of food‐waste (25% compared with 10%) did not produce VFA proportionally due to the increased rate of conversion of VFA into gaseous products. The maximum VFA production rate (0.318 g VFA_produced g^?1 VS_fed day^?1) was achieved in the 10 wt % food‐waste at ambient temperature and at a 5‐day HRT. Copyright © 2005 Society of Chemical Industry     

历史中心区复兴中的地域性问题与对策

本文以上海思南路47～48街坊改造为例,探讨城市形态更新与居民外迁问题,并期待相关地域性社会对策的出现。     

企业施工定额的编制以及施工成本分析平台的应用

本文阐述了施工企业内部编制定额的必要性和成本分析平台的实用性,并根据多年的工作经验就建筑施工企业对施工成本的控制谈谈一自己的认识和看法.     

一维弹道修正模块设计与仿真

简要介绍了一种用于维弹道修正引信的执行机构。通过数学模型，结合MDT三机械设计软件和Working Model动力学仿真软件，对机构的受力情况和工作过程进行了数字仿真和系统分析，并通过对飞行弹道的模拟，得出了一维时间控制射程修正规律。     

锂离子电池正极材料锂锰氧化物的固相合成研究进展

阐述了固相合成反应的原理，综述了锂锰氧化物的几种固相合成方法，并着重介绍了熔融渍法，多步加热法，机械化学法和微波化学法等在锂锰氧化物合成中的研究进展。     

液态混合有机标准物质研究

本研究采用重量法配制有机液态混合标样 ,并对配制方法、混合标样的均匀性、稳定性及影响不确定度的因素进行了研究 ,并用气相色谱法进行了比对分析。经稳定性监测 ,稳定度大于等于一年 ,不确定度小于± 2 %。     

铝电解槽磁流体稳定性有限元分析

本文采用有限元法求解分层磁流体小扰动方程系统特征值，研究铝电解槽稳定性。研究结果表明，在没有电磁力时，铝液表面波动（内波）是稳定的。存在电磁力时，它会激发铝液表面波动的某些低频长波分量不稳定性，高频短波不受影响。被激发的不稳定波动频率和扰动增长率与电流密度，磁感应强度垂直分量，铝电解槽长宽比，电解质和铝液的密度差，厚度等因素密切相关。减少电流密度，磁感应强度，增加电极距离和铝液厚度可以提高铝电解槽的稳定性。这对铝电解槽优化设计和在线控制有重要意义。