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371.
基于PSO优化逻辑斯蒂曲线的水资源安全评价模型 总被引:1,自引:0,他引:1
论文引入“压力-状态-响应”框架模型构建区域水资源安全定量评价的指标体系,采用逻辑斯蒂(Logistic)曲线模拟区域水资源安全评价,公式中的参数采用粒子群算法(PSO)进行优化,并用灵敏度分析的方法对公式进行了可靠性分析。优化好的Logistic指数公式用于安徽省16个地级市水资源安全评价,计算得到各地级市评价指数和相应的评价等级,并对压力层、状态层、响应层子系统进行分析。评价结果表明,基于粒子群算法优化的Logistic指数公式用于区域水资源安全评价,具有合理性和可行性,能为区域水资源规划与管理决策提供科学依据。 相似文献
372.
Min Gong Li Wu Xiang-yang Bi Li-min Ren Lei Wang Zhen-dong Ma Zheng-yu Bao Zhong-gen Li 《Environmental geochemistry and health》2010,32(1):59-72
Nine potentially harmful heavy metals (Cd, Co, Cr, Cu, Hg, Mn, Pb, Ni, and Zn) were measured in 477 topsoil samples collected
from urban–rural areas in the city of Wuhan in order to identify their concentrations and possible sources, and characterize
their spatial variability for risk assessment. Results showed that in most rural areas heavy-metal concentrations in soil
were similar to their natural background values, but Cd, Cu, Hg, Pb, and Zn concentrations were relatively higher in densely
populated districts and around industrial facilities. Multivariate analyses (correlation matrix, principal component analysis,
and cluster analysis) indicated that Cd, Cu, Hg, Pb, and Zn were mainly derived from anthropogenic inputs, and Co, Cr, and
Mn were controlled by natural source, whereas Ni appeared to be affected by both anthropogenic and natural sources. The result
of risk assessment indicated that nearly 48% of the study area suffered from moderate to severe contamination. 相似文献
373.
以多种理论模型对非饱和土三轴仪实测数据进行了拟合评价;并在此基础上,引入非饱和土最新理论,反演和解析了土体脱湿与吸湿条件下的边界土-水特征曲线、渗透系数函数以及吸应力特征曲线;进一步从强度本构入手,结合不同基质吸力的三轴剪切试验结果,探究了基于吸应力的强度特性。研究结果表明:非饱和土三轴仪所测数据点及其三种模型拟合曲线均落在水力边界曲线(SWCC、HCF、SSCC)范围之内,表明了试验结果的正确性和合理性,以及非饱和土中水分的能量和数量的关系因路径差异而具可变性,即基质吸力不再是含水率的单值函数,而是一个范围体系;同时采用吸应力特征曲线的统一有效应力原理来描述土体在非饱和条件下的抗剪强度性质是合理的、普遍有效的,并且验证了土体处于饱和或者无基质吸力时,吸应力不为零,此时的吸应力对应的是土体在剪切破坏时的表观粘聚力这一结论。 相似文献
374.
375.
氧化偶合混凝法处理废水,是使其中的有机污染物在氧化剂的诱导作用下,发生偶合或聚合而被混凝过滤去除。本文采用低剂量Fenton试剂诱导氧化偶合混凝法处理苯酚及其衍生物模拟废水,取得良好效果。通过对苯酚氧化过程的分析及分子量分布的测定,证实了反应过程中确有偶合产物生成,并通过顺磁共振波谱(ESR)的研究及偶合产物结构的质谱(GC/MS)鉴定,推测了偶合反应的机理。该偶合反应为自由基偶合反应,偶合产物是由C-C键或C-O键联接而成的。 相似文献
376.
沈阳地区过去30年环境风险时空格局的研究 总被引:1,自引:1,他引:0
应用“风险频数”及相关指标对沈阳地区过去30年环境风险的时空格局进行了分析。结果表明:风险频数在1966—1977及1978—1991两个时段之间的分布存在极显著差异(t=-7.353,t0.01=2.807);过去30年环境风险空间分布格局没有显著变化,但各亚区之间风险频数存在显著差异;沈阳地区存在一批高风险企业,化工行业是风险最高行业。 相似文献
377.
Recovery of phosphorus(P) from wastewater is of great significance for alleviating the shortage of P resources. At present, the P recovery process is faced with the problem of excessive organic carbon consumption when obtaining a P-concentrated recovery solution. This study proposed a new strategy to obtain a more highly concentrated P recovery solution with minimal carbon consumption by strengthening the P storage capacity of the biofilm. A biofilm sequencing batch reactor(BSBR) process was mod... 相似文献
378.
379.
Seasonal aerosol samples have been collected by Andersen Hi-Vol pumping system equipped with a five stage cascade impactor
and a backup filter (size range: 10–7.2 μ m, 7.2–3.0 μ m, 3.0–1.5 μ m, 1.5–0.95 μ m, 0.95–0.49 μ m, ≤0.49 μ m) in the Liwan
district, Guangzhou. n-Alkanes were measured using gas chromatography and PAHs were measured using gas chromatography/mass spectrometry analysis.
The bimodal log-normal distributions of n-alkanes and semi-volatile PAHs were found, while for non-volatile PAHs that was unimodal, so much as the mode of semi-volatile
PAHs was similar with that of the particles. The n-alkanes and PAHs were preferably associated with fine particles. C
max (carbon number maximum) (C22–C26), CPI (carbon preference index) (1.12–1.21), U/R (unresolved to resolved components ratio) (7.42–10.7), wax% (0.9–3.12%)
and the diagnostic ratios for PAHs revealed that vehicular emission was the major source of these organic compounds during
the study periods, while the contribution of epicuticular waxes emitted by terrestrial plants was minor. CPI2 (values for petrogenic hydrocarbons), CPI3 (values for biogenic n-alkanes) and wax% revealed that the natural preferentially accumulated in the larger aerosol while the anthropogenic in the
smaller. In addition, the different MMDs (mass median diameters) for n-alkanes and PAHs were observed in different seasons. The MMDs for n-alkanes and PAHs were higher in autumn/winter than those in spring/summer. The seasonal effect was related to the hydrocarbon
content in the individual particulate fractions, showing a preferential association of n-alkanes and PAHs with larger particles in the autumn/winter season. 相似文献
380.