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41.
42.
Chen B Pan Y Wang J Fu Z Zhang Y Zhou Y 《Environmental monitoring and assessment》2012,184(6):3545-3556
Evenly distributed sampling design is generally considered as an efficient sampling design. It is widely used in sampling
for the environmental survey. In this paper, we present a novel method for generating N evenly distributed samples within a given irregular polygon via simulating the movements of some ideal homogeneous point
charges. Initially, charges are randomly put into the sampling region; then, they are freed and held orderly; and after enough
runs, the charges will finally reach a stable state with all of them having a zero resultant force and velocity; and so they
distribute evenly within the region. Their layout can thus be considered as an evenly distributed sampling design. The main
advantages of this method are: (1) it is easy to understand and implement; (2) it is efficient in both running and generating
better designs. Analysis and experimental results indicate that this method is an efficient and robust method for generating
even sampling designs for 2D polygonal sampling region. 相似文献
43.
构建阶式生物接触氧化反应器处理富营养化太湖水源水,对其净水效能进行研究。结果表明,在优化工况条件下,阶式生物氧化反应器的三阶对太湖水源水中DOC的累积去除率分别为34.4%、40.2%和47.5%,对BDOC的总去除率为68.4%,除生物降解外,填料拦截、生物吸附絮凝等物理、化学作用对去除原水中的DOC仍有重要作用。DOC分子量分级表明,太湖源水中含量最大的是分子量〈500Da的DOC,含量最小的是分子量在5k~500Da间的DOC。阶式生物接触氧化反应器对分子量〈500 Da的DOC的去除率在60%以上,而出水中5k~500 Da区间的DOC含量相比原水增加近1倍。 相似文献
44.
Adsorption of Pb(II) on variable charge soils amended with rice-straw derived biochar 总被引:11,自引:0,他引:11
Two Ultisols and one Oxisol from tropical regions of southern China were incubated with rice straw biochar to investigate the effect of biochar on their surface charge and Pb(II) adsorption using batch methods. The incorporation of biochar induced a remarkable increase in soil cation exchange capacity after 30 d of incubation. The incorporation of biochar significantly increased the adsorption of Pb(II) by these variable charge soils; the enhancement of adsorption of Pb(II) by these soils increased with the addition level of biochar. Adsorption of Pb(II) involved both electrostatic and non-electrostatic mechanisms; however, biochar mainly increased Pb(II) adsorption through the non-electrostatic mechanism via the formation of surface complexes between Pb2+ and functional groups on biochar. There was greater enhancement of biochar on the non-electrostatic adsorption of Pb(II) by the variable charge soils at relatively low pH. Therefore, the incorporation of biochar decreased the activity and availability of Pb(II) to plants through increased non-electrostatic adsorption of Pb(II) by acidic variable charge soils. 相似文献
45.
聚丙烯酸钠作为调理剂对好氧堆肥的保氮影响 总被引:2,自引:0,他引:2
实验以污泥、锯末、猪粪为原料,以聚丙烯酸钠(PAAS)为调理剂,利用自制好氧堆肥反应器,研究了PAAS在污泥好氧堆肥中的保氮效果。实验显示,PAAS会提高堆体的pH水平,抑制氨氮的生成,从而减少NH3的挥发源,在PAAS对水溶性氨的吸附作用下,堆肥产品的最终氨氮水平依然得到提高;PAAS对硝化反应有一定的促进作用,添加PAAS的堆体在堆肥周期内的硝氮平均增幅可达到未添加PAAS的空白堆体的4.64倍;添加PAAS的堆体在堆肥周期内全氮平均降幅只有空白堆体的52.24%。PAAS做为堆肥调理剂起到了较为明显的保氮效果。 相似文献
46.
桥梁实用延性抗震设计方法研究 总被引:1,自引:1,他引:1
针对铁路桥梁中应用广泛的单柱式桥墩 ,考虑多种跨度 ,多种墩高和多种场地及多种地震烈度的情况 ,在进行大量的桥墩结构线性和非线性弹塑性动力计算分析的基础上 ,通过对大量数据的统计分析 ,得到桥墩线弹性最大弯矩比和非线性位移延性比参数的变化规律 ,基于概率性的结构随机地震反应理论 ,建立了由线弹性动力分析结果来估算桥墩结构的位移延性响应的方法。 相似文献
47.
随着工、农业的发展,洞庭湖区域的环境污染日趋严重。本文较详细地研究了洞庭湖区域的环境整治规划,在各环境要素的规划方面进行了探讨。 相似文献
48.
222Rn, 226Ra, 228Ra and U were determined in a total of 552 groundwater samples collected throughout Fujian Province of China. The geometric mean concentrations of 222Rn, 226Ra, 228Ra and total U in the groundwater were 147.8 kBq m-3, 12.7 Bq m-3, 30.2 Bq m-3 and 0.54 microgram kg-1, respectively. High groundwater 222Rn was explained by the predominantly granitic rock aquifers in Fujian. A lifetime risk of 1.7 x 10(-3) was estimated for the ingestion of groundwater 222Rn. High ratios of 228Ra to 226Ra contents (geometric mean of 2.4) and their disproportion suggest that 228Ra should also be measured in the assessment of population doses from drinking water in the regions of high rock or soil 232Th. No significant correlation between the 222Rn concentrations in groundwater and air was found. 相似文献
49.
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