TEM室法环天线校准系统建立及测量结果不确定度评定

横电磁波室法是9 kHz～30 MHz频段环天线校准中广泛采用的一种方法.环天线分为有源环天线和无源环天线两类,这两种天线的磁场天线系数在量值范围上差别大,对系统动态范围要求不同.根据这一特点,对两类环天线分别建立横电磁波室作为标准场的环天线校准系统,基于网络分析仪开展扫频测量.针对电磁兼容领域中常用的直径60 cm以...     

芦山地震中大跨空间结构主要破坏模式及数值分析

为探究短边距混凝土网架平板支座的受力机理和破坏模式,分别针对不同混凝土边距以及不同钢底板开孔形式共3个平板支座缩尺试件进行拟静力试验。对平板支座试件的破坏模式、滞回曲线、混凝土柱上层箍筋应变进行分析。试验结果表明：采用规范中对抗剪锚筋混凝土边距的建议长度,不能避免支座混凝土边缘破坏发生,但是混凝土柱上层箍筋对混凝土边缘的约束作用明显,并且采用开长孔钢底板并合理设计开孔长度,能有效推迟甚至避免发生混凝土边缘破坏。     

建筑装饰用铜合金的表面钝化工艺与性能研究

采用化学浸渍法在装饰用H62铜合金表面制备了不同转化膜,优化了单一稀土盐和复合（Ce+La）盐转化膜的钝化液配方,对比分析了未加稀土盐、单一Ce盐、单一La盐和（Ce+La）盐试样的耐蚀性能和作用机理。结果表明,单一稀土盐的钝化液中硝酸镧/硝酸铈含量为8%时的转化膜具有最佳的耐腐蚀性能;复合（Ce+La）盐最优钝化工艺为硝酸镧/硝酸铈=4/4 g/L、C₆H₅N₃浓度15 g/L、Na₂MoO₄浓度2 g/L、C₆H₈O₇浓度13 g/L、C₇H₆O₆S.2H₂O浓度9 g/L、SDBS浓度0.2 g/L、钝化温度48℃、钝化时间4 min;不同转化膜试样的硝酸点滴、中性盐雾、静态浸泡腐蚀和电化学腐蚀性能测试结果具有一致性,即耐性能从低至高顺序为：未加稀土盐<单一Ce盐<单一La盐<（Ce+La）盐,在钝化液中添加稀土盐有助于提高转化膜膜层厚度,并增强转化膜的耐蚀性能,且复合添加（Ce+La）盐可获得相对单一稀土盐更好的钝化效果。     

扫描拉曼埃分辨显微术:一种新的分子化学结构解析方法

针尖增强拉曼光谱(TERS)技术由于其超高的空间分辨与灵敏的化学识别能力,在纳米尺度的结构表征和物理化学性质的分析中发挥着重要作用。本文首先回顾了高分辨TERS技术的近期发展与应用,并对高分辨成像的潜在物理机理进行了简要概述,接着介绍一种由超高分辨TERS成像衍生出来的新的分子化学结构解析方法―扫描拉曼埃分辨显微术(SRP),最后对SRP技术的进一步发展进行了展望。     

基于“雁阵效应” 的扑翼飞行机器人高效集群编队研究

本文借鉴“雁阵效应”, 研究了扑翼飞行机器人高效集群编队飞行问题. 通过对“V”字雁阵的分析得知, 当前排大雁(简称头雁)和后排大雁(简称从雁)保持某一合适的相对位置偏移时, 后排大雁可有效利用前排大雁挥翅产生的上洗涡流, 从而节省体能; 并且, 雁阵通过阵型的变换, 可以实现能量整体消耗的均衡性, 确保长航时飞行. 仿照该“雁阵效应”, 分析得出耗能最少的扑翼飞行机器人集群阵型排布方式, 并设计了阵型变换机制, 实现集群能量整体消耗的最优性和均衡性. 在此基础上, 参考雁群的交互方式, 设计了一种使用局部信息的控制方法, 保证最优阵型的稳定维持以及阵型间的灵活变换. 最后, 仿真结果验证了所提理论结果的有效性.     

基于加速残差网络的图像超分辨率重建方法

针对深层网络架构的图像超分辨率重建任务中存在网络参数多、计算复杂度高等问题,提出了一种基于加速残差网络的图像超分辨率重建方法.首先,构建一个残差网络对低分辨率图像与高分辨率图像之间的高频残差信息进行重建,以减少冗余信息的深层网络传输过程,提高重建效率;然后,通过特征收缩层对提取的低分辨率特征图进行降维,从而以较少的网络...     

多次采动影响巷道高预应力桁架锚索支护技术

为解决多次采动下巷道围岩控制难题,采用理论分析、现场试验的方法,提出了高预应力桁架锚索支护系统原理,该系统设置的同轴式连接紧缩器对拉预紧,使顶板岩层处于形成多向挤压状态,有效改善巷道围岩应力环境,高预紧力、桁架结构、锚索良好的延伸率使其具有"先刚"、"先抗"、"后柔"、"后让"的支护特点,现场应用验证了技术参数的合理性...     

Superior reinforcement in polyamide 1010/multiwalled carbon nanotube composites realized by high‐rate drawing and incorporation of compatibilizer

To realize the full potential of carbon nanotubes (CNTs) in polymer/CNT nanocomposites, many complicated chemical treatments have been developed to modify the CNTs. Nevertheless, the reinforcing efficiency is still not satisfactory in most cases. In this study, a dramatically improved mechanical enhancement is obtained for polyamide 1010/multiwalled carbon nanotube (MWNT) composites simply by exerting high‐rate drawing and incorporating a commercially available compatibilizer. For the fibers prepared at high draw ratio, their tensile strength and modulus are improved by 137 and 132%, respectively, through adding only 0.5 wt% MWNTs. In particular, the increase in strength is at a very high level for the case of non‐covalent interaction since CNTs could be stretched to failure according to theoretical calculation. It is demonstrated that this reinforcement is mainly attributed to the compatibilizer inducing good dispersion, and the high‐rate drawing inducing strong interfacial interaction and orientation of MWNTs. Copyright © 2012 Society of Chemical Industry     

硅钢退火炉氮气冷却的碳套辊分析

阐述了传统硅钢退火炉无冷却碳套辊的缺点,并介绍和分析了通氮气冷却碳套辊的技术特点。     

Effects of halloysite in kaolin on the formation and properties of geopolymers

A kaolin containing 31 wt.% halloysite and a relatively pure kaolin were selected to study the effects of halloysite on the dissolution behavior of precursors and the formation of geopolymers. The Al and Si concentrations in the leached solutions were studied by inductively coupled plasma-optical emission spectrometry (ICP-OES). The reaction process of metakaolin–activator mixtures was monitored by isothermal conduction calorimetry (ICC) while the reaction products were examined by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and mercury intrusion porosity (MIP). Results showed that the halloysite containing kaolin and its metakaolin possessed higher Si and Al dissolution rate than the purer kaolin and its metakaolin. When mixed with sodium silicate activator at 20 °C, the presence of halloysite in kaolin led to a higher geopolymerization rate of metakaolin as reflected by the heat evolution rate. The presence of halloysite improved the reactivity of metakaolin but did not change the geopolymerization pathway under 20 °C air curing and 80 °C steam curing conditions. The products from the two metakaolins had a similar XRD characteristic (i.e. a typically amorphous diffraction). Only a minor difference in the pore distribution and the porosity was found between those products from the two sources of metakaolins.