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951.
952.
为有效提高煤矿瓦斯浓度动态预测精度,基于微分方程理论和最小二乘法,从灰色预测模型静态灰色作用量出发,优化灰色作用量,推导幂指数型灰色作用量的改进灰色瓦斯浓度预测算法,推导基于集成学习不同灰色作用量幂指数型灰色瓦斯预测模型,进而研究吉林八连城长期和短期瓦斯浓度监控数据预测精度。结果表明:瓦斯浓度时间序列近似线性时,基于集成学习的改进灰色瓦斯浓度预测算法优于传统灰色瓦斯浓度预测算法,使瓦斯浓度预测值和实际值的均方根误差降低,均方根差最大降低2.25%。研究结果可有效提瓦斯浓度预测精度。 相似文献
953.
Elo H 《Die Naturwissenschaften》2007,94(9):779-780
The ionization potential of one-electron ions can be calculated from a well-known simple equation, but no such equation has
been available for calculating the ionization potential of multi-electron ions. I report here an equation that accurately
gives the ionization potential of helium-like (i.e., two-electron) ions as a function of the atomic number, the relative difference
from experimental values being below 1% for all ions for which reliable experimental data were found (Z = 3–29). The equation also predicts the stability of the negative hydrogen ion (the hydride ion), H−, although with twice too large a value for the ionization potential. 相似文献
954.
HUANG Ze-chun AN Zhi-zhuang CHEN Tong-bin LEI Mei XIAO Xi-yuan LIAO Xiao-yong 《环境科学学报(英文版)》2007,19(6):714-718
In order to understand the similarity or difference of inorganic As species uptake and transport related to phosphorus in As-hyperaccumulator, uptake and transport of arsenate (As(Ⅴ)) and arsenite (As(Ⅲ)) were studied using Pteris vittata L. under sand culture. Higher concentrations of phosphate were found to inhibit accumulation of arsenate and arsenite in the fronds of P. vittata. The reduction in As accumulation was greater in old fronds than in young fronds, and relatively weak in root and rhizome. Moderate increases, from 0.05 to 0.3 mmol/L, in phosphate reduced uptake of As(Ⅲ) more than As(Ⅴ), while the reverse was observed at high concentrations of phosphate (≥ 1.0 mmol/L). Phosphate apparently reduced As transport and the proportion of As accumulated in fronds of P. vittata when As was supplied as As(Ⅴ). It may in part be due to competition between phosphorus and As(Ⅴ) during transport. In contrast, phosphate had a much smaller effect on As transport when the As was supplied as As(Ⅲ). Therefore, the results from present experiments indicates that a higher concentration of phosphate suppressed As accumulation and transport in P. vittata, especially in the fronds, when exposure to As(Ⅴ); but the suppression of phosphate to As transport in the root or rhizome may be insignificant when P. vittata when exposure to As(Ⅲ) under sand culture conditions. The finding will help to understand the interaction of P and As during their uptake process in P. vittata. 相似文献
955.
异养硝化细菌Bacillus sp. LY脱氮性能研究 总被引:1,自引:1,他引:0
研究了异养硝化细菌Bacillus sp. LY的脱氮性能.结果表明,Bacillus sp. LY是1株具有脱氮能力的异养硝化细菌.在NH+4-N浓度分别为40、80和120 mg/L 3种情况下,120 h反应后,氨氮的去除率分别是100%、85.7%、73.7%,总氮的去除率分别是76.6%、53.4%、64.8%,在菌液初始浓度相同的情况下,随着NH+4-N浓度的增加,细菌的硝化速率以及脱氮速率呈现下降的趋势.有机物浓度是影响Bacillus sp. LY脱氮性能的重要因素,低的有机物浓度会阻碍细菌脱氮性能的发挥,中的有机物浓度会促进细菌脱氮性能的发挥,使体系的脱氮效果达到最佳,高的有机物浓度并不能再次提升细菌的脱氮性能.在Bacillus sp. LY作用下,有机氮经过氨化作用生成氨氮,通过2条可能的途径转化为氮气.1条途径是氨氮先硝化生成亚硝酸盐与硝酸盐,然后反硝化生成氮气.另1条途径是氨氮被氧化生成羟胺,然后脱氢生成氧化亚氮并进一步转化为氮气.这些研究可为开发新型高效生物脱氮工艺提供参考. 相似文献
956.
用于湿法净化黑烟表面活性剂筛选的数学模型研究 总被引:2,自引:0,他引:2
湿法净化燃煤窑炉中的黑烟,关键在于表面活性剂对炭黑的润湿、增溶和降低表面张力作用.根据研究筛选的数学模型,计算AEO-9和SDBS混合表面活性剂溶液的亲水亲油平衡值HLB、临界胶束浓度CMC与胶束形成吉布斯自由能ΔG0mf.通过实验测得不同配比AEO-9和SDBS溶液的CMC和处于该CMC时黑烟的去除效率η,分析混合溶液中HLB、CMC、ΔG0mf与η的关系,建立新的数学模型.结果表明,理论CMC与实测CMC吻合度较好;HLB与ln[CMC]线性相关;ΔG0mf与η存在二次函数关系.降低CMC可以有效增大HLB,增加溶解度,减小形成胶束的吉布斯自由能,降低表面张力,使形成胶束的反应更容易自发进行,有效提高黑烟去除效率. 相似文献
957.
958.
959.
针对某化工厂硫酸生产中,由于硫酸生产中受冶炼烟气SO2浓度影响波动较大、冶炼系统故障以及自身工艺技术等因素的制约,化工厂硫酸生产系统尾气SO2浓度在烟气非正常条件下(烟气中SO2浓度小于3.5%),甚至在烟气正常条件下(烟气中SO2浓度大于3.5%)有时均难以达标排放,不但造成大量含SO2的尾气超标排入大气,而且使得大... 相似文献
960.
Sulfamethoxazole (SMX) is one of the most common detected antibiotics in the environment. In order to study whether SMX can
a ect behavior and growth and whether these e ects could be transferred to the progeny, Caenorhabditis elegans was exposed at
environmentally relevant concentrations for 24, 48, 72 and 96 hr, respectively. After exposure, the exposed parent generation (P0)
was measured for behavior and growth indicators, which were presented as percentage of controls (POC). Then their corresponding
unexposed progeny (F1) was separated and measured for the same indicators. The lowest POC for P0 after 96 hr-exposure at 100
mg/L were 37.8%, 12.7%, 45.8% and 70.1% for body bending frequency (BBF), reversal movement (RM), Omega turns (OT) and
body length (BL), respectively. And F1 su ered defects with the lowest POC as 55.8%, 24.1%, 48.5% and 60.7% for BBF, RM, OT
and BL, respectively. Defects in both P0 and F1 showed a time- and concentration-dependent fashion and behavior indicators showed
better sensitivity than growth indicator. The observed e ects on F1 demonstrated the transferable properties of SMX. Defects of SMX
at environmental concentrations suggested that it is necessary to perform further systematical studies on its ecological risk in actual
conditions. 相似文献