Analysis of energy embodied in the international trade of UK

Interest in the role embodied energy plays in international trade and its subsequent impact on energy security has grown. As a developed nation, the UK's economic structure has changed from that of a primary producer to that of a primary consumer. Although the UK's energy consumption appears to have peaked, it imports a lot of energy embodied in international trade alongside the more obvious direct energy imports. The UK has seen increasing dependency on imported fossil energy since the UK became a net energy importer in 2005. In this paper an energy input–output model is established to calculate not only the amount of fossil energy embodied in UK's imports and exports, but also the sector and country distributions of those embodied fossil energy. The research results suggest the following: UK's embodied fossil energy imports have exceeded embodied fossil energy exports every year since 1997, UK embodied energy imports through the so-called ‘Made in China’ phenomena are the largest accounting for 43% of total net fossil energy imports. If net embodied fossil energy imports are considered, the gap between energy consumption and production in UK is much larger than commonly perceived, with subsequent implications to the UK's energy security.     

基于自组织模糊神经网络溶解氧控制方法研究

针对污水处理过程中溶解氧浓度难以控制的问题,提出了一种基于自组织模糊神经网络（self-organizing fuzzy neural network, SOFNN）的溶解氧（dissolved oxygen, DO）控制方法。首先,采用激活强度和神经元重要性两个评判标准,来判断神经元对网络的贡献及活跃程度。然后,对不活跃的神经元进行删减,以此来对神经网络结构进行自适应的调整,从而满足实际控制要求,提高控制精度。其次,采用梯度下降算法对SOFNN神经网络的各个参数进行实时调整,以保证网络的精度。最后,将该自组织方法用在Mackey-Glass时间序列预测中,结果表明所提出的自组织模糊神经网络具有较好的预测效果;同时将所提出的SOFNN方法在BSM1仿真平台上进行实验验证。结果表明,所提出的自组织模糊神经网络控制方法能够对溶解氧浓度进行较好地控制,具有一定的自适应能力。     

埋地管道抗震强度的理论分析探讨

针对目前埋地管道地震应力简化计算公式中存在的问题,本文采用弹性地基梁法,以结构动力学理论和地震波动力学理论为基础,推导了地震行波有夹角入射地下管道的运动微分方程和管土间的位移传递系数,得出横波、纵波具有相同的位移传递系数,进而求得管道的最大应变及应力。最后通过采用不同方法及本文方法进行实例分析,认为本文方法与实际情况较符合。     

结合NAT穿透的应用层组播方案的设计

针对流媒体直播系统的数据传输,设计了一个应用层组播方案,结合NAT穿透技术构建和维护支持不同种类局域网通信的组播树。该方案的核心内容是提出了一个改进的目的驱动最短路径算法,使用网络传输延迟作为度量值构建低代价最短路径树,可以使从源节点到目的节点的传输延迟最小,并且尽可能减少带宽消耗。组播树维护策略能有效的重构组播拓扑结构,增强组播树的健壮性。     

两种透明介质微小折射率差高精度测量的新方法

对现有折射率的测量技术进行分析,提出了一种测量两种透明介质间微小折射率差的新方法。首先,介绍了微小折射率差干涉测量方法的原理,并对该测量原理利用Zemax光学仿真软件进行了理论模拟论证。该实验中首先,采用热键合技术制备包含两种被测量材料的组合平板;其次,利用干涉测量仪及外光路测量样件界面区域不同入射角下的光程差;再者,利用几何光学中的折射定律,推导折射率分布与干涉光程差的关系式。最后,通过二次曲线拟合获得正入射时的光程差微小变化值、换算得到样件两种材料的折射率差值。实验测量了1 at.% Yb3+::YAG晶体与YAG晶体的热键合样品的折射率差,测量值为5.4110-5,测量系统精度10-7量级。结果表明:该测量方法原理简单、操作简便,测量精度高。     

Na_（1/2）Bi_（1/2）TiO_3基无铅压电体系退极化行为的研究进展

简述了钛酸铋钠[Na1/2Bi1/2TiO3,BNT]的相变过程及其退极化现象,介绍了退极化温度的确定方法,概述了NBT基复合体系准同型相界（MPB）附近的退极化行为,总结了有关退极化温度影响机制的几种观点。借鉴PbTiO3基高温压电体系的研究,提出采用具有小允差因子的Bi基钙钛矿Bi（B′B″）O3作为第二组元,与BNT形成新型无铅压电复合体系,以求提高MPB处的退极化温度,并简述了相关的研究报道。     

圆钢管混凝土边框多重组合低矮剪力墙的抗震性能

为了解钢管混凝土边框内藏钢桁架剪力墙这种新型多重组合剪力墙的抗震性能,进行了3个剪跨比为1.0的低矮剪力墙低周反复荷载试验,包括1个普通混凝土剪力墙、1个圆钢管混凝土边框剪力墙和1个圆钢管混凝土边框内藏钢桁架剪力墙;对比分析了3个低矮剪力墙的实测承载力、延性、刚度及其退化过程、滞回特性、耗能能力及破坏特征;使用简化力学模型计算了各剪力墙的承载力,计算结果与试验结果吻合较好。结果表明:圆钢管混凝土边框内藏钢桁架低矮剪力墙的抗震性能比普通混凝土低矮剪力墙显著提高,比圆钢管混凝土边框低矮剪力墙明显提高。     

大功率GaN基白光LED荧光层失效机理研究

在某些情况下长期服役,发现部分白光发光二极管(LED)器件表面出现黑色物质,影响了光的转换和取出。采用切割剖面、扫描电镜(SEM)和能量弥散光谱仪(EDS)等微区分析手段,辅以电流和温度加速应力实验,对部分老化后表面出现变黑现象的芯片进行分析,发现变黑样品的C与Si的原子数比是13.21,高于未变黑样品(8.45)。而有机材料在温度和光照条件下会发生降解碳化,这是LED封装失效的主要原因,与芯片本身无关,验证了高温是最主要的失效因素,光照影响也不可忽略。芯片和封装材料膨胀系数不匹配造成的界面应力、长时间蓝光照射引起的光降解和光热耦合作用造成了器件灾变性失效。     

Application of Task-Oriented Method of Serial Robot for Mechanism Analysis and Evaluation

Revealing the relations among robotic comprehensive performance, configuration, scales and working tasks is the basis to optimize robotic mechanism. Due to the correlation and diversity of the single performance indexes, statistical principles of linear dimension reduction and nonlinear dimension reduction are introduced into comprehensive performance analysis and evaluation for typical serial robot. The robotic mechanism＇ s configuration, scales and task with the best comprehensive performance can be obtained by principal component analysis （PCA） and kernel principal component analysis （KPCA） respectively. The results show that KPCA can reveal the nonlinear relations among different single performance indexes more effectively and provide more comprehensive performance information than PCA. Thus, task-oriented method of serial robot for mechanism analysis and evaluation is proposed, which also provides scientific research basis for the mechanism synthesis and optimmn task order.     

多电极介质阻挡放电降解甲苯的实验研究

介质阻挡放电是产生低温等离子体的有效方法.为了增大电晕区影响范围,提高对甲苯的降解能力,本实验在常温常压的环境下,研究了"多电极等离子反应器".实验考察了反应器结构、电场强度、频率、气体流速对甲苯去除率的影响,分析了放电电压与漏失电流的关系.实验结果表明,反应器结构对去除率有显著的影响,高压放电极数量的增加有利于提高去除率,反应器漏失电流随外加电压的增大而增大.甲苯的去除率随电场强度的增强而增大、随气体流速的增大而减小.甲苯的去除率随频率的增强而增大,但频率对去除率的影响不如场强的效果显著.