浅析小电流接地系统暂态选线新方法

文章介绍了国内小电流接地系统故障选线方法的的发展简况,在分析小电流接地故障暂态特征的基础上对近几年提出的几种较新的基于暂态特征信息的选线方法进行了简单的评述,同时筒略说明了不足之处.文章最后提出了一种基于暂态能量函数的小电流接地选线方法,并有待于进一步研究.     

The effect of MWCNTs on the performance of α-sexithiophene OTFT device and its gas-sensing property

In this paper,bottom contact organic thin-film transistor(OTFT)gas sensors were prepared.Silicon dioxide(SiO2)and titanium/aurum(Ti/Au)were used as the insulating layer and the electrode for the device,respectively.The multi-walled carbon nanotubes(MWCNTs)/α-sexithiophene(α-6T)bilayer films were used as the active layer,andα-6T single layer sensitive film was also prepared for comparison purpose.The electrical and trace NO2-sening properties of these two OTFT gas sensors were tested and analyzed.The results showed that,the OTFT device based on MWCNTs/α-6T bilayer had obviously better electrical properties,better stabilities and higher NO2-sening response values than the device withα-6T single layer,in which both the carrier mobility(μ)and on/off current ratio enhanced two order of magnitude.The improved performance of bilayer OTFT can be explained that MWCNTs acted as highly conducting bridges connecting the crystalline terraces in theα-6T film.Threshold voltage(VT),carrier mobility,on/off current ratio and grid current which showed extremely similar variation trend as source-drain current,were optional parameters to reveal the gas-sensing characteristic of OTFT gas sensors.Morphology analysis showed that the special feature of MWCNTs had certain influence on the gas-sensing properties.     

上海地区冬季住宅室内外颗粒物浓度的相关性

对上海市某住宅建筑室内外PM10、PM2.5、PM1的浓度进行了测量,研究了最小通风量（外门窗关闭）条件下3种天气时颗粒浓度随时间变化的规律以及相关性,分析了颗粒物浓度与环境温湿度参数之间的关系.研究结果显示,测试期间,室内外空气中细颗粒（PM 2.5）占可吸入颗粒（PM 10）浓度比例分别达65％和87％以上;无明显室内源时,I/O比值小于1且随粒径减小而减小;室内外颗粒浓度相关性与粒径大小有关系,PM1、PM2.5的浓度相关性大于PM10.研究还表明,颗粒物浓度的关联性与天气状况有关系,多云、雨天和阴天时浓度关联性有显著差别;颗粒物的浓度受到室内外温湿度的影响,且受天气状况影响而呈现复杂性.     

用于FBG解调的光纤F-P可调滤波器温漂抑制

光纤法布里-珀罗可调滤波器(FFP-TF)是组成光纤布拉格光栅(FBG)传感器解调系统的核心器件之一,其稳定性对解调精度的提高至关重要,而温度漂移是影响其稳定性的关键因素之一。针对实际应用中遇到的FFP-TF温漂问题,分析了温漂产生的原因和滤波器在给定驱动电压下中心波长随温度的变化关系,提出了一种温度控制与参考光栅相结合的复合温漂抑制方法,实验分析了相应温控装置的性能并将其成功用于FBG压力传感器的信号解调系统中。结果表明,基于该温漂抑制方法的FFP-TF解调方案,可广泛应用于FBG传感器系统中。     

基于组合优化BP神经网络的模拟电路故障诊断

电子系统的可靠性已成为影响系统正常运行的关键,因此电路故障的诊断越来越受到重视。基于BP神经网络的诊断方法是目前实现模拟电路故障诊断的有效方法之一。文章针对已有BP神经网络模拟电路故障诊断技术的不足,提出了一种组合优化的诊断方案。该方案采用遗传算法优化确定BP神经网络的初始权值,以规避BP神经网络易陷入局部极小值的不足,然后应用L-M方法在这个局部解空间里对BP神经网络进行精调,搜索出最优解或者近似最优解。该方案发挥了BP神经网络的广泛映射能力和遗传算法的全局搜索能力,加快了网络的学习速度,综合提高了整个学习过程中的逼近能力和泛化能力,有效提升了基于BP神经网络模拟电路故障诊断的性能。     

The oxidation state of sulfur detected in Na2O-CaO-SiO2 float glass by X-ray absorption near edge structure spectra

The oxidation state of sulfur is detected in Na2O-CaO-SiO2 float glass by synchrotron radiation X-ray absorption near edge structure (XANES) spectra at the sulfur K edge. The measured spectra show the only presence of S6+ in the Na2O-CaO-SiO2 float glass and the oxidation state of sulfur do not change with the increase of glass depth. It is also found that, after the melt has gone through the molten tin bath, the S6+ is the dominant species, but S2- is also present on both surfaces. It is not certain whether cation bonds to S2- or not, because there are many cations dissolved in the melted tin which makes the spectrum complicated.     

Fabrication and thermal insulating properties of ATO/PVB nanocomposites for energy saving glass

The pechini method was used to synthesize antimony-doped tin oxide (ATO) nanoparticles, and the subsequent solution co-blend was employed to fabricate ATO/PVB nanocomposites. Uv-Vis-NIR spectra show that the addition of ATO nano particles can significantly enhance the thermal insulating efficiency of ATO/PVB nanocomposites. With the increase of ATO content, the thermal insulating efficiency is increased. Uv is almost fully absorbed by all ATO/PVB nanocomposites. Vis transmittance-haze spectra reveal that ATO/PVB nanocomposites exhibit higher Vis transmittance of over 72.7% and lower haze of below 2% when ATO content is in the range of 0.1 wt%–0.5 wt%. The thermal insulating tests indicate that in comparison with the pure PVB film, nanocomposite films with 0.1 wt%–0.5 wt% ATO can reduce temperature of 1–3 °C, suggesting that this novel nanocomposite can be used for energy-saving glass.     

基于文化管理视角的高职院校内涵建设探析

高职院校内涵建设的关键在于推行“以人为本”的文化管理模式．在具体的管理实践中,应当渗入人性化思想,把受文化支配的人的思想和情感作为重要指标,加强信念及价值观的培育,并充分发挥其在管理中的作用．这既是对传统教育管理机制的一种突破,也是对新型教育管理模式的创建．因此,厘清文化管理的特征、把握文化管理的原则、探索实施文化管理的思路和策略,具有理论和现实的双重意义．     

盐酸曲美他嗪的合成

研究一种冠状动脉血管扩张剂盐酸曲美他嗪的合成方法。以六水哌嗪为起始原料,经酰化、Mannich反应、水解、成盐反应制得目标化合物。目标化合物的结构经熔点测定、红外及1 H-NMR谱确证,总收率为29.2%,经HPLC检测纯度为98.5%。该合成方法成本较低、操作简便、条件温和,适于工业生产。     

大跨度复杂钢结构施工力学模拟的研究与应用

随着我国经济的发展,大跨度空间钢结构的形式也日趋复杂,施工过程对结构的影响不能忽略.结构施工过程中的力学问题属于施工力学的范畴,是耦合了时间与空间的四维分析.采用施工力学方法对三个大跨度复杂钢结构工程进行施工过程跟踪模拟分析,同时将有限元计算结果同实际监测结果进行对比.研究表明:进行施工过程模拟分析不仅可以优化施工方案,而且可以保证施工过程中结构的安全并使成型结构的内力和变形满足设计要求.在此基础上,给出一些关于大跨度复杂钢结构施工的建议和意见,为施工力学学科的研究和发展提供了参考.