黑碳气溶胶的光散射特性研究

利用光电检测法研究黑碳气溶胶粒子的光散射特性,根据粒子的光散射特性来分析它的尺度谱.黑碳气溶胶粒子在激光的作用下产生散射光,利用光电检测器检测黑碳气溶胶粒子发出的散射光.提出了利用散射光信号的前沿部分进行拟合,得到粒子散射光信号的完整高斯分布.     

利用激光雷达观测芜湖市上空气溶胶光学特性

利用Mie散射激光雷达对芜湖市上空的气溶胶光学特性进行观测研究,从观测数据中选取降雨和降雪天气的特例,通过计算反演得到了雨、雪天气前后气溶胶粒子的光学厚度、气溶胶粗粒子比例以及粒子数密度的变化情况,经分析得出雨、雪对气溶胶粒子具有一定的洗刷作用。从科学的角度验证了雨、雪是大气重要的自清洁过程,并初步得到了同等条件下,雪比雨对空气清洁能力更强的结论。     

基于光衰减法的黑碳气溶胶浓度检测系统设计

在研究一种大气黑碳气溶胶浓度检测系统的基础上,提出了一种基于光衰减法的黑碳气溶胶浓度检测方法。首先,从理论上分析了基于光衰减法的黑碳气溶胶浓度检测与反演。然后,重点介绍了光电检测电路的硬件设计和气溶胶浓度反演算法的软件设计。最后,通过计算机上管理软件显示并分析检测结果。运行结果表明该检测系统达到了预期设计目标。     

宝鸡市一次污染过程黑碳气溶胶的变化特征及潜在源解析

利用AE-31型黑碳仪于2019年2月4-26日对宝鸡市的黑碳(BC)气溶胶进行了在线连续监测,并结合PM2.5质量浓度、风速风向等数据,采用聚类分析研究了该地区污染期间BC质量浓度的变化及来源.结果表明,观测期间BC平均质量浓度为2.8μg·m-3,范围为0.4～8.0μg·m-3;PM2.5平均质量浓度为119.9...     

气溶胶光学吸湿增长特性测量方法研究进展

吸湿性气溶胶会吸收环境空气中的水分,其粒径会随相对湿度的增加而发生变化,从而导致气溶胶的光学特性(如消光、散射、吸收系数与单次散射反照率等)发生显著的变化。气溶胶光学吸湿增长因子(湿状态与干状态下光学参数的比值)是衡量气溶胶光学吸湿增长能力的特征参数,是计算大气能见度和气溶胶辐射强迫的关键输入量,它的准确测量对于气溶胶环境和气候效应的评估具有重要意义。光学吸湿增长测量系统主要包括湿度调节系统和光学测量装置,通过湿度调节系统改变样品的相对湿度,再结合光学测量装置实时测量光学参数的变化,从而实现光学吸湿特性的在线测量。鉴于气溶胶吸湿性研究的重要意义,重点分析对比了现有的光学吸湿增长测量方法及应用,并对下一步气溶胶光学吸湿增长特性测量技术和研究方向做了展望。     

合肥地区气溶胶数浓度和谱分布特征的观测研究

利用APS-3321型空气动力学粒度仪对合肥地区的大气气溶胶进行观测,比较和分析了气溶胶数浓度和谱分布的变化特征.结果表明:气溶胶数浓度的日变化和日际变化显著,并且与天气条件密切相关.其平均数浓度谱为单峰谱,峰值中心在聚集模态,平均表面积谱和平均质量谱为双峰谱,峰值中心分别在聚集模态和粗模态,且其最大峰值都在聚集模态.根据其谱分布特征,应用正态对数函数进行了拟合,得到了其数学函数表达式,该结果可用于分析气溶胶对大气激光传输的影响.     

用MFRSR仪器观测气溶胶光学厚度

气溶胶对激光大气传输有着重要的影响。MFRSR(多光谱旋转遮蔽影带辐射计)是一种用于地基辐射和气溶胶测量的仪器。该仪器使用自动旋转影带技术同时在七个波段交替进行总的水平辐射和漫射水平辐射测量,然后推算得出直接辐射。其中6个波段的中心波长分别是414.3nm,495.3nm,613.7nm,671.5nm,867.6nm,939.3nm,还有一个硅探测器进行宽波段太阳总辐射测量。本文首先介绍了MFRSR仪器及其定标和资料处理方法,然后利用香河观测站2004-2005年MFRSR观测资料,分析了气溶胶的统计特性。为了说明利用MFRSR观测气溶胶光学厚度的可靠性,我们将MFRSR与AERONET的观测结果进行了比较,结果表明二者在500nm、670nm和870nm三个波段的平均偏差分别为-0.021,-0.009,-0.004;标准差分别为0.067,0.051,0.050。文中还对造成二者偏差的原因进行了讨论。     

厦门海域气溶胶光学特性的观测研究

在讨论了太阳辐射计标定的基础上,介绍了利用多波段太阳辐射计对厦门海域气溶胶光学厚度的测量.研究测量结果表明厦门海域气溶胶的Jungle参数是3.0017,它具有大陆模式的特性.     

二次有机气溶胶光学特性研究进展

二次有机气溶胶 (SOA) 对大气能见度、辐射平衡、气候变化具有重要影响, 系统地研究不同环境因素对 SOA 光学性质的影响是大气科学研究的前沿性方向。外场观测是认知 SOA 光学性质的重要途径, 近年来新的观测仪 器和模型的发展使得对 SOA 光学性质的认识更加深入。而实验室研究通过控制特定变量模拟不同条件下 SOA 的生 成过程, 从机制上加深了对 SOA 光学特性的认知。综述重点关注了近年来有关经气相氧化、多相过程等途径生成的 SOA 的光学特性研究, 并分析了老化过程对 SOA 光学特性的影响, 以及外场和实验室结果的对比和联系。     

大气棕碳气溶胶吸光特性影响因素的研究进展

棕碳 (BrC) 是大气中一类重要的吸光性含碳气溶胶, 因其对区域乃至全球辐射强迫和气候具有显著影响而备 受关注。然而, 对大气中 BrC 吸光特性缺乏全面认识是导致其辐射强迫评估不确定性的关键因素之一。通过梳理近 年来国内外 BrC 吸光特性的相关研究, 发现 BrC 来源、发色团组成、大气过程、 pH 条件和共存金属等都是影响 BrC 吸光特性的潜在因素, 系统总结了现有研究中对 BrC 吸光特性影响因素及影响机制的认识, 并对未来 BrC 吸光特性及 影响因素相关的研究方向提出了建议与展望.     

碳黑用量对硅橡胶压阻材料性能的影响

以高导电纳米碳黑为导电填料,甲基乙烯基硅橡胶为基材,制备出了硅橡胶压阻材料,并对其电性能和力学性能进行了表征。研究了碳黑用量对硅橡胶压阻材料电性能、压缩应力松弛性能以及电阻蠕变性能的影响。结果表明,碳黑用量对硅橡胶压阻材料的性能影响很大。当碳黑用量为质量分数14%~16%时,所制得的硅橡胶压阻材料性能优良,在反复加载20次的过程中,其压阻曲线的重复性很好,这为其下一步的器件化提供了可能。     

芳香化合物生成二次有机气溶胶的光学性质研究进展

芳香化合物是二次有机气溶胶(SOA)的一类重要前体物,其在大气中的氧化可以生成具有光吸收特性的棕色碳。因此,理解芳香化合物所生成SOA的光散射、光吸收、反照率等光学性质对于定量研究其对空气质量、能见度和气候变化的影响具有重要意义。系统总结了实验室研究中单环芳香烃、含氧芳香化合物、多环芳香烃三类典型芳香化合物所生成SOA的光学性质,分析对比了文献关于光散射和光吸收参数的异同,归纳了多种环境因素对SOA光学性质的影响,并展望了该方向未来的重点研究领域。     

Effect of the fabrication method on the electrical properties of poly(acrylonitrile-co-butadiene-co-styrene)/carbon black composites

Poly(acrylonitrile-co-butadiene-co-styrene) (ABS), an engineering plastic, was combined with carbon black (CB) to increase its conductivity. The ABS/CB composites were prepared using two different methods: dissolution of ABS in Butan-2-one and manual mixing of the constituent materials. These fabrication methods led to different microstructures, which led to vastly different electrical properties. The microstructures were acquired using scanning electron microscopy (SEM) and optical microscopy, while the electrical conductivity was obtained using impedance spectroscopy. The percolation threshold of the composites fabricated using the manual mixing method was found to be much lower (0.0054 vol.% CB) than that of the composites fabricated using the dissolution method (2.7 vol.% CB).     

Template free titiania photoanodes modified with carbon black or multi-wall carbon nanotubes: Thermal treatment at low and high temperature for the fabrication of quasi-solid state dye sensitized solar cells

A simple procedure was developed to prepare modified titiania (TiO₂) photoanodes for dye sensitized solar cells at low and high temperature in order to improve overall cell efficiency. Modification of TiO₂ films achieved by the incorporation of either carbon black powder (CBP) or multi-wall carbon nanotubes (MWCNTs). A small quantity of titanium alkoxide was added in a dispersion of titiania (TiO₂) powder consisting of nanoparticles at room temperature, which after alkoxide׳s hydrolysis helps to the connection between titiania (TiO₂) particles and to the formation of mechanically stable relatively thick films on conductive glass substrates. The absence of surfactant allowed us to prepare films at relatively low temperature (~100 °C), while the effect of sintering at a higher temperature (500 °C) was also studied. The structural properties of the films were examined with porosimetry method and microscopy analysis. Better electrical results were obtained for the MWCNT (0.1 wt%) modified TiO₂ films, with 3.14% and 4.68% conversion efficiencies under 1 sun illumination after treatment at 100 °C and 500 °C, respectively. The enhancement in photocurrent for MWCNT-TiO₂ films compared to pure TiO₂ films is attributed to the improved interconnectivity between TiO₂ nanoparticles, which further improved the electron transport through the film. For carbon doped CBP-TiO₂ cells, lower efficiencies were observed compared to pure TiO₂.     

Improving the electrical and mechanical behavior of electrically conductive paint by partial replacement of silver by carbon black

Partial replacement of silver particles by carbon black (low cost) in electrically conductive paint was found to decrease the electrical resistivity and increase the scratch resistance of the resulting thick film, which is for use in electrical interconnections. An effective carbon black content is 0.055 of the total filler volume. By using a total solid volume fraction of 0.1969 and a silane-propanol (1:1 by weight) solution as the vehicle, a paint that gives a thick film with resistivity 2 × 10⁻³ Ω·cm has been attained.     

Synthesis of carbon nanotubes by catalytic chemical vapour deposition: A review on carbon sources,catalysts and substrates

Carbon nanotubes (CNTs) have been extensively studied during the past two decades and Catalytic Chemical Vapour Deposition (CCVD) technique has been untiredly employed by researchers to produce CNTs of various crystallographic configurations. In this paper the material aspects carbon sources, catalysts and substrates with regard to CCVD synthesis of carbon nanotubes are reviewed in light of latest developments and understandings in the field. The role of these materials in synthesis of CNTs is explained keeping the upto date literature in view. Latest research reports and their findings are presented with regard to effects of growth control aspects such as temperature, vapour pressure and catalyst concentration on CNT formation. Besides recent understandings with regard to preferential growth of CNTs are also discussed. From this literature review it is found that carbon diffusibility and carbon solubility of any catalyst are two important factors in determining CNT nucleation and growth. Moreover, addition of catalyst species to any transition metal catalyst can improve the catalyst performance and addition of water, air, alcohol etc. during CCVD process can increase the activity and lifetime of the catalyst besides enhances the production of CNTs.     

Segmentation of moving objects in image sequence: A review

Segmentation of objects in image sequences is very important in many aspects of multimedia applications. In second-generation image/video coding, images are segmented into objects to achieve efficient compression by coding the contour and texture separately. As the purpose is to achieve high compression performance, the objects segmented may not be semantically meaningful to human observers. The more recent applications, such as content-based image/video retrieval and image/video composition, require that the segmented objects be semantically meaningful. Indeed, the recent multimedia standard MPEG-4 specifies that a video is composed of meaningful video objects. Although many segmentation techniques have been proposed in the literature, fully automatic segmentation tools for general applications are currently not achievable. This paper provides a review of this important and challenging area of segmentation of moving objects. We describe common approaches including temporal segmentation, spatial segmentation, and the combination of temporal-spatial segmentation. As an example, a complete segmentation scheme, which is an informative part of MPEG-4, is summarized.     

碳点离子液体复合物的制备及其在超级电容器中的应用

以1-甲基-3-乙基咪唑四氟硼酸离子液体和果糖为原料,微波作用下一步制得一种新型碳点离子液体复合物,用此复合物代替部分导电剂和粘结剂制成新型炭基超级电容器,并与传统的炭基超级电容器进行了比较研究。结果表明:所制复合物中有大量直径小于4nm的碳纳米粒子,70℃时电导率达到13.26×10–3S·cm–1。所制超级电容器充放电效率由传统炭基超级电容器的89.1%提高到97.3%,比电容由115.7 F.g–1提高到251.1 F·g–1,内阻由1.95Ω 降低为1.23Ω ,且循环性能显著提高。