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971.
采用CFD软件Fluent研究了不同壁面加热条件下街道峡谷内流场及污染物浓度分布情况.结果表明,当街道高宽比(H/W)为1.33时,在低风速(u=1m/s)条件下,当壁面与周围大气无温差时,街道峡谷内存在一个稳定的顺时针大漩涡,污染物在背风侧堆积.当背风面、地面和背风面分别被加热时,峡谷内流场分布与无温差时相似,此时峡谷内的湍流强度增强,导致污染物浓度降低.当迎风面被加热时,峡谷内流场由原来的单漩涡结构变为双漩涡结构,此时街道峡谷下部浓度较高,上部浓度相对较低.当地面和迎风面同时被加热,温差较小(?θ=2℃)时,街道峡谷内流场由单漩涡结构变为双漩涡结构; 温差增大为5℃,峡谷内由双漩涡分裂成了3个漩涡,此时污染物分布与迎风面被加热情况相似.通过实测值和模拟值的比较可知,Fluent软件对街道峡谷大气环境的模拟结果基本合理. 相似文献
972.
Geochemistry of the barkinite liptobiolith (Late Permian) from the Jinshan Mine,Anhui Province,China
This paper discusses the geochemistry and mineralogy of the barkinite liptobiolith of the Late Permian age from the Jinshan
Mine, Guangde County, Anhui Province, China. Samples were examined using inductively coupled plasma-mass spectroscopy, X-ray
fluorescence, cold-vapor atomic absorption spectrometry, ion-selective electrode, sequential chemical extraction, scanning
electron microscopy equipped with energy-dispersive X-ray, and optical microscopy. The coal is a medium-ash and high-sulfur
resource. Minerals in the coal are composed of kaolinite, pyrite, calcite, and quartz. Pyrite and calcite are derived from
seawater during peat accumulation. Quartz in the coal is of authigenic origin. Part of the kaolinite is from a land-source
region, and part occurs as cell-fillings and is of authigenic origin. The results also indicate that the barkinite liptobiolith
contains some toxic elements in high concentrations. Elements including Li, Be, Si, Sc, Ti, V, Cr, Fe, Ga, Se, Y, Zr, Mo,
the rare earth elements (REEs), W, Hg, Tl, Pb, Th, and U in the coals are enriched in the barkinite liptobiolith. Results
of sequential chemical extraction showed that Li, Sc, Ti, Cr, Y, Zr, REEs, and Th in the coal mainly occur as silicates, while
Be and W are related to organic matter. Pyrite is the dominant source of S, Mo, Hg, Tl, and Pb. Gallium only occurs in silicate,
and U and V occur both in organic and silicate associations. 相似文献
973.
974.
975.
Gao Ya Wu Zhibin Li Weiming Sun Haibo Chai Youzheng Li Tianyou Liu Chao Gong Xiaomin Liang Yunshan Qin Pufeng 《Environmental science and pollution research international》2023,30(2):2355-2373
Environmental Science and Pollution Research - Waste mushroom substrate (WMS) generated in large quantities from mushroom production process has caused severe environmental pollution. As a... 相似文献
976.
Zhai Yuanzheng Ma Tianyi Zhou Jingjing Li Xiaofei Liu Dan Wang Zhuo Qin Yunqi Du Qingqing 《Environmental science and pollution research international》2019,26(6):5713-5723
Environmental Science and Pollution Research - Colloids associated with heavy metals are ubiquitous in contaminated groundwater; waste accumulation at imperfectly sealed landfills can produce large... 相似文献
977.
Wang Mengke Peng Qin Zhou Fei Yang Wenxiao Dinh Quang Toan Liang Dongli 《Environmental science and pollution research international》2019,26(10):9730-9738
Environmental Science and Pollution Research - Selenite and selenate are two main selenium (Se) forms absorbed by plants. The comparative effects of selenite and/or selenate on Se uptake and... 相似文献
978.
全自动驾驶是一种先进的轨道交通列车运行控制技术,在全自动驾驶模式下,轨道交通列车运维对站台门的安全提出了更高的要求。本文在分析站台门在全自动驾驶模式下的安全监控需求的基础上,从站台门的运行外部环境和站台门自身的运行参数两方面出发,建立站台门智能安全监控系统,实时全面掌握站台门的安全状态,基于BIM技术和自适应学习技术,对站台门的安全状态进行预测,防范于未然并及时做好维修计划调整。该系统能让站台门的安全处于主动控制状态,减少安全隐患。 相似文献
979.
Hui-Fen Zhang Hao Qin Bao-Cai Li Yi Qin Huan-Hong Wang Bing Zhang 《Journal of the Air & Waste Management Association (1995)》2020,70(10):980-989
ABSTRACT Montan resin (MR) is a by-product produced during the refinement process of montan wax extracted from lignite and has no usage yet. Chemical modification is an effective method to change the material property for expanding or converting the application area of the material itself. Our previous study found that the high hydrophobicity of MR is the primary limiting factor for its utilization in agriculture. Based on this point, this study attempted to chemically modify MR using the oxidation of peracetic acid, resulting that the MR hydrophilicity was significantly improved, and a water-soluble product (WSP) was obtained. The optimized oxidation conditions of MR, including the reaction temperature (X1), reaction time (X2), weight ratio of oxidant and montan resin (X3), and oxidant concentration (X4), were determined using single-factor experiments and response surface analysis. The modification degree was evaluated using elemental and oil-water partition coefficient analyses, infrared (IR) spectroscopy, and gas chromatography-mass spectrometry (GC-MS), revealing that the oil-water partition coefficient of the modified product decreased and that the number of chemical constituents with oxygen-containing functional groups clearly increased after modification. Furthermore, the WSP was tested its effects on germination and seedling growth of the wheat seed. Compared with the control group, the WSP showed a promoting effect on the growth and germination of wheat. The WSP concentrations of 600 mg·L?1 and 300 mg·L?1 had the most substantial effect on the root and seedling growth of wheat, respectively. Implications: Montan resin, a useless by-product produced from crude montan wax, was chemically modified via oxidation of peracetic acid. Its hydrophilicity was significantly improved, and a water-soluble product was obtained after the chemical modification. The optimized oxidation conditions of montan resin were determined using single-factor experiments and response surface analysis. The amount of chemical constituents with oxygen-containing functional groups increased in the modified products after modification, as determined by IR and GC-MS analysis, among other methods. The water-soluble modified product showed an obvious effect in promoting growth and germination of wheat at 600 mg·L-1 and 300 mg·L-1, respectively. 相似文献
980.
不同还原药剂修复Cr(Ⅵ)污染土壤的稳定性评估 总被引:1,自引:0,他引:1
针对目前铬污染场地修复后的长期稳定性问题,选用轻、重污染土壤和表层渣土混合物为研究对象,在分析其理化特性的基础上,对经CaS_4、FeSO_4·7H_2O和葡萄糖还原后土壤的长期稳定性进行评估,通过设置干燥和淹水2个条件,探究了水分对Cr(Ⅵ)污染土壤长期稳定性的影响。结果表明:针对3种不同类型铬污染土壤,投加CaS_4对土壤中Cr(Ⅵ)的还原效果较FeSO_4·7H_2O和葡萄糖好;在360 d的采样周期内,干燥条件下的3种土壤经CaS_4处理后Cr(Ⅵ)浓度均保持稳定,经FeSO_4·7H_2O和葡萄糖药剂还原后,渣土混合物中Cr(Ⅵ)波动幅度较大,其余2种土壤呈稳定状态;淹水密闭条件下的3种土壤中Cr(Ⅵ)浓度均有下降趋势,特别是渣土混合物在投加FeSO_4·7H_2O和葡萄糖药剂处理后,下降趋势更为明显;在长期稳定性方面,在360 d的实验周期内,与淹水密闭条件相比,经还原修复后的Cr(Ⅵ)污染土壤在干燥条件下的稳定性更强;Cr(Ⅵ)污染土壤经还原后,有效的过量还原剂能在一定程度上抑制土壤中Cr(Ⅵ)浓度变化,且在淹水密闭条件下,土壤中Cr(Ⅵ)浓度呈下降趋势。 相似文献