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151.
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Junyao Li Weiqi Xu Zhijie Li Minzheng Duan Bin Ouyang Shan Zhou Lu Lei Yao He Jiaxing Sun Zifa Wang Lin Du Yele Sun 《Indoor air》2021,31(5):1364-1376
Most of human exposure to atmospheric pollutants occurs indoors, and the components of outdoor aerosols may have been changed in the way before reaching indoor spaces. Here we conducted real-time online measurements of mass concentrations and chemical composition of black carbon and the non-refractory species in PM2.5 in an occupied office for approximately one month. The open-close windows and controlled dampness experiments were also performed. Our results show that indoor aerosol species primarily originate from outdoors with indoor/outdoor ratio of these species typically less than unity except for certain organic aerosol (OA) factors. All aerosol species went through filtration upon transport indoors. Ammonium nitrate and fossil fuel OA underwent evaporation or particle-to-gas partitioning, while less oxidized secondary OA (SOA) underwent secondary formation and cooking OA might have indoor sources. With higher particulate matter (PM) mass concentration outdoors than in the office, elevated natural ventilation increased PM exposure indoors and this increased exposure was prolonged when outdoor PM was scavenged. We found that increasing humidity in the office led to higher indoor PM mass concentration particularly more oxidized SOA. Overall, our results highlight that indoor exposure of occupants is substantially different from outdoor in terms of mass concentrations and chemical species. 相似文献
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In order to explore the application of organic conjugated small molecules in bioimaging, a novel functional chromophore with A-π-D-π-A structure (Cr-3) was synthesized through Knoevenagel condensation reaction, consisting of carbazole unit as electron donor and cyanoacetic acid as electron acceptor groups. To improve the water solubility of this conjugated molecule, three carboxyl groups were introduced to chromophore Cr-3. Compared to the traditional D-π-A chromophores, chromophore Cr-3 showed the great improvement in water with the solubility of 2000 ppm. Also, the thermal stability of chromophore Cr-3 was also studied. The thermal decomposition temperature (Td) of Cr-3 was approximately 180°C, which was attributed to the dehydration of the carboxyl groups. Though the second harmonic generation (SHG) effect was not very high, it is large enough for the detection of SHG signal in water solution (0.28 pm/V). 相似文献
155.
To investigate the impacts of ambient pressure on thermal runaway and fire behaviors of lithium‐ion battery (LIB), experimental measurement and theoretical analysis with serial conditions are conducted at two altitudes. The well‐designed experimental equipment and operating conditions have enabled the accurate evaluation of ambient pressure effects. Results show that the first abrupt temperature change in Hefei (ambient pressure 100.8 kPa) is higher than that in Lhasa (64.3 kPa). The difference in ambient pressure at two altitudes leads to different relief valve crack temperature and time. The average burning rate in Hefei is larger than that in Lhasa, and the estimated pressure effect factor is quite different for detailed pack conditions and varies within the range of 0.083‐1.39. The ambient pressure has a greater effect on the heat release rate and total heat release than the mass loss, and the effective combustion heat under the low pressure is lower than that in normal condition. This work can provide more comprehensive and useful data for the safety management of LIBs at low pressure environments. 相似文献
156.
This study performs data-driven modeling of mesoscale solids stress closures for filtered two-fluid model (fTFM) in gas–particle flows via an artificial neural network (ANN) based machine learning method. The data used for developing the ANN-based predictive data-driven modeling framework is systematically filtered from fine-grid simulations. The loss function optimization result reveals that coupling two loss functions promotes more accurate predictions of the mesoscale solids stresses than using a single loss function. Further comprehensive assessments of closure markers demonstrate a systematic dependence of the mesoscale solids stresses on the filtered particle velocity and its gradient as additional anisotropic markers, instead of using the conventional isotropic filtered rate of solid phase deformation as a closure marker. An optimal three-marker mesoscale closure is thus proposed. Comparative analysis of the conventional filtered model and present three-marker model shows that the data-driven model can substantially enhance the prediction accuracy. 相似文献
157.
Passenger thermal comfort and behavior: a field investigation in commercial aircraft cabins 下载免费PDF全文
Passengers' behavioral adjustments warrant greater attention in thermal comfort research in aircraft cabins. Thus, a field investigation on 10 commercial aircrafts was conducted. Environment measurements were made and a questionnaire survey was performed. In the questionnaire, passengers were asked to evaluate their thermal comfort and record their adjustments regarding the usage of blankets and ventilation nozzles. The results indicate that behavioral adjustments in the cabin and the use of blankets or nozzle adjustments were employed by 2/3 of the passengers. However, the thermal comfort evaluations by these passengers were not as good as the evaluations by passengers who did not perform any adjustments. Possible causes such as differences in metabolic rate, clothing insulation and radiation asymmetry are discussed. The individual difference seems to be the most probable contributor, suggesting possibly that passengers who made adjustments had a narrower acceptance threshold or a higher expectancy regarding the cabin environment. Local thermal comfort was closely related to the adjustments and significantly influenced overall thermal comfort. Frequent flying was associated with lower ratings for the cabin environment. 相似文献
158.
Xuesong Li Xiaoping Ouyang Xiaobing Pan Guanyi Wei Jing Tu 《Journal of Nuclear Science and Technology》2013,50(5):520-524
Two groups of 129I and 127I targets were analyzed using a gas quadrupole mass spectrometer (QMS) to determine the transmutation rates via the melting method. Sodium iodide was chosen to make the target. The iodine composition in the 129I targets is 82.7% 129I and 17.3% 127I. The transmutation rate of the 129I(n, γ)130I reaction was determined by measuring the 130Xe with QMS. An equivalent corrective method was brought out to correct the 129I(n, 2n)128I branch which is interfered with by the 127I(n, γ)128I reaction. And the correction formula was deduced in theory. For very little 128Xe from the 129I(n, 2n)128I reaction, the equivalent corrective method could not be suitable here. However, it is suitable for the mass of 128Xe from 129I(n,2n)128I reaction that reaches the accurately detective level of the mass spectrometry. 相似文献
159.
针对武汉地区混合式热泵系统在运行时出现的热积累现象,利用Fluent软件建立武汉地区某办公楼的冷却塔-土壤源热泵模型,并在传统的温差控制策略的基础上提出两种控制策略——夜间冷却塔运行策略和夜间热泵制热工况运行策略.通过模拟研究,比较3种控制策略的优缺点,发现夜间热泵制热工况运行的控制策略可对土壤起到较好的降温作用,可有效解决系统长期运行热积累的问题. 相似文献
160.