复杂液体光谱法分析的浓度分辨率及浓度分布影响

为保证基于光谱技术的复杂溶液检测的可行性,分析多波长建模对浓度分析的精度增益,以及确定合适的组分浓度分布以得到质量高、普适性佳的定量分析模型,从光谱检测仪器噪声、光谱数据多波长建模和被测溶液成分浓度分布影响因素入手,对复杂溶液成分浓度检测精度的影响进行分析。通过对浓度分辨率分析,对已知光谱仪噪声条件下能够实现的溶液成分浓度分辨率进行评估,也为在已知定量分析所需浓度分辨率条件下选择满足测量要求的光谱仪器提供理论依据。基于过采样提高测量精度技术分析,表明多波长建模带来了精度增益,从而提高浓度检测灵敏度。考虑被测成分含量以及非测量成分的含量在所测范围内疏密比和加权欧氏距离,为选择满足浓度分布的有利于提高模型质量、减小预测误差的样本集进行建模提供理论指导。

基于本征荧光的生物气溶胶测量激光雷达性能

为研究本征荧光对生物气溶胶粒子探测精度的影响,本文在阐述生物气溶胶荧光光谱信号探测原理的基础上,设计了一台紫外激光诱导荧光雷达.该雷达选用波长为266 nm的四倍频固体激光器作为激励光源,基于本征荧光波长、探测距离等主要参数,对生物气溶胶荧光光谱回波信号的信噪比及粒子浓度的最小分辨率进行数值仿真分析.仿真结果表明,在探测误差小于10%的情况下,距离为1.5 km时,系统对生物气溶胶荧光波长的有效探测范围为300—800 nm;而在距离为2.1 km时,荧光波长的有效探测范围为300—310 nm.此外,在探测距离定义为0.1 km,荧光波长为350和600 nm时,系统对物气溶胶粒子浓度的最小分辨率分别为2个颗粒/L和4个颗粒/L,最小分辨率的差值为2个颗粒/L.仿真结果有利于了解荧光波长变动时激光雷达系统的探测准确度,进而实现大气生物气溶胶更加有效的探测.

基于多层PCB的ME-C^(4)D电极设计及其性能研究

文章针对微芯片电泳电容耦合式非接触电导检测(microchip electrophoresis-capacitively coupled contactless conductivity detection, ME-C^(4)D)电极存在检测信号信噪比低、稳定性差的问题,提出一种基于多层印制电路板(printed circuit board, PCB)的ME-C~4D电极。通过与相同结构的单层PCB电极对比实验发现,多层PCB电极的噪声最大电平降低至5.5 mV、信噪比提升1倍,且检测信号具有较好的稳定性。通过实验对多层PCB电极结构参数进行优化,使检测系统对K^(+)、Na^(+)、Li^(+)3种离子混合溶液的检测限和离子浓度分辨能力达到0.050 mmol/L,且检测结果具有较好的线性度和可重复性。实验证明,采用多层PCB电极,不仅改善了ME-C^(4)D系统的检测灵敏度和离子浓度分辨率,同时扩大了系统的最佳离子浓度检测范围。

Estimation of total suspended matter in the Zhujiang (Pearl) River estuary from Hyperion imagery

Although remote sensing data have been used to estimate total suspended matter （TSM） in coastal waters, it has limitations when applied to estuary waters in low spatial resolution situations. The spatial resolution of ocean color satellites such as SeaWiFS and MODIS is usually -1 km, and therefore is not adequate for small, local-scale areas such as the Zhujiang （Pearl） River estuary. In contrast, 30 m-resolution EO-1 Hyperion imagery has potential for studying TSM in localized areas. We measured the surface spectral radiance reflectance of the river estuary water in the visible and near infra-red spectral range. Sensitivity analysis indicated that the ratio of remote sensing reflectance at 813 nm （Rrs（813）） to reflectance at 559 nm （Rrs（559）） could be used to estimate TSM concentration, and a linear relationship was established between the ratio and in-situ TSM concentration. We applied the linear relationship to Hyperion imagery to map TSM concentration in the estuary. The Hyperion imagery provided sufficient spatial resolution to detect spatiotemporal changes in TSM concentrations in the estuary small estuary area. This study demonstrated the usefulness of Hyperion imagery for mapping the distribution of TSM in estuary waters. Keyword： Hyperion; total suspended matter （TSM）; Zhujiang （Pearl） River estuary

Assessment of total suspended sediment concentrations in Poyang Lake using HJ-1A/1B CCD imagery

We explored the potential of the environment and disaster monitoring and forecasting small satellite constellations (HJ-1A/1B satellites) charge-coupled device (CCD) imagery (spatial resolution of 30 m, revisit time of 2 days) in the monitoring of total suspended sediment (TSS) concentrations in dynamic water bodies using Poyang Lake, the largest freshwater lake in China, as an example. Field surveys conducted during October 17-26, 2009 showed a wide range of TSS concentration (3-524 mg/L). Atmospheric correction was implemented using the Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) module in ENVI with the aid of aerosol information retrieved from concurrent Terra/Moderate Resolution Imaging Spectroradiometer (MODIS) surveys, which worked well at the CCD bands with relatively high reflectance. A practical exponential retrieval algorithm was created between satellite remote sensing reflectance and in-situ measured TSS concentration. The retrieved results for the whole water area matched the in-situ data well at most stations. The retrieval errors may be related to the problem of scale matching and mixed pixel. In three selected subregions of Poyang Lake, the distribution trend of retrieved TSS was consistent with that of the field investigation. It was shown that HJ-1A/1B CCD imagery can be used to estimate TSS concentrations in Poyang Lake over synoptic scales after applying an appropriate atmospheric correction method and retrieval algorithm.

Urban Air Quality Assessment of Kathmandu by Passive Sampling Technique

This paper presents an assessment of air quality of the Kathmandu valley, capital city of Nepal. This is the largest urbanized area in the country of about 300 km2. In the last two decades an intensive development of demographic, traffic and industry growth in the region was observed which was reflected on the air quality degradation. In order to evaluate the urban air quality in Kathmandu, a field monitoring network for particle deposition, nitrogen dioxide （NO2） and sulphur dioxide （SO2） by passive sampling with high space resolution was implemented in co-operation with IVL-Sweden. The net work composed of 60 monitoring sites distributed in a grid of 1 × 1 km2 covering all over the main city and some rural valley. Monitoring were carried out for two seasons, rainy and dry as two campaign monitoring. The diffusive samplers were prepared and analyzed in IVL, Sweden. Good agreements in particle deposition between the two campaigns were observed. The particle deposition to the surrogate surface varied between 3 and 608 μg@cm2·monthl for the monitoring periods. The NOz concentrations on the other hand were quite similar in the two campaigns, and the SO2 concentrations were much lower in the first campaign compared to the second. The ranges of NO2 and SO2 concentrations were found to be from 5.6 to 52.6 μg/m3 and 0.6 to 23.4 μg·m-3 respectively. Arc Info/Arc map GIS 9.2 software was used for production of maps of spatial distribution of all the three parameters in the valley. Seasonal variation and traffic influence were also studied. Local meteorological effects in the distribution of pollutants were clearly observed and the NO2 concentrations were strictly related with traffic intensity.