响应面法用于优化污水厂脱氮工艺的研究

在单因素试验基础上,采用Box-Behnken响应面法对新疆某联合式污水厂的脱氮单元进行优化,结果表明,对脱氮性能的影响由强到弱依次为碳氮比(C/N)、有机负荷(F/M)和内回流比(R).模型优化后的最佳工况条件C/N为7.45、R为52.61％、F/M为0.10 d-1,污水厂在该工况下进行验证试验,其NH3-N、TN平均去除率分别为87.23％、91.20％,在出水中的测定均值分别为0.37 mg/L、6.09 mg/L,均满足一级A标准.NH3-N和TN去除率与预测值相对误差分别为0.38％和0.55％,与模型预测值较接近.     

建筑施工高处坠落事故研究

高处坠落是建筑施工中经常发生的安全事故之一。笔者首先通过对上海市 1995～ 2 0 0 1年建筑施工安全事故档案资料的统计整理 ,发现建筑施工高处坠落事故主要集中在建筑物临边、洞口 ,脚手架、操作平台 ,机械设备和模板工程等部位 ;进而采用曲线拟合的方法得到了上海市建筑施工安全事故年发生起数的预测模型 ,并通过对 2 0 0 2年、2 0 0 3年的预测值同实际数据的比较 ,对预测模型进行了验证 ;最后 ,笔者按照事故致因理论 ,从人、物、环境等因素系统分析了高处坠落的事故原因 ,提出了预防坠落的控制措施和有关建议。     

Odour from municipal solid waste (MSW) landfills: a study on the analysis of perception

The objective of this work was to develop a relationship between odour intensity and odour concentration by using data collected from various sensitive areas of the municipal solid waste (MSW) landfill site. A number of well-known psychophysical models (e.g., Weber-Fechner law, Steven's power law, Beidler's and Laffort's models) have been discussed that can successfully relate the perceived intensity with the odour concentration. Respective parameters for each of the models were estimated by the nonlinear Levenburg-Marquardt parameter estimation method. The overall performance of the model was tested statistically against sets of data from the olfactometry analysis. The model based on the Weber-Fechner law was ranked 1 in case of five out of nine samples and it has been found more representative of the less intense odour samples. The model based on Laffort's equation has represented the intensity-concentration relationship better with extremely low uncertainties on both parameters k1 and k2 for comparatively more intense odour samples.     

复杂矿井通风系统分支阻力可调性数值研究

笔者应用数字实验方法 ,通过调节分支阻力 ,研究它对通风系统的影响。研究结果表明 :当一些分支的阻力调到接近完全隔断风流的极大值时 ,网络分析结果仍然正常 ,不影响迭代技术 ;同样也说明了分支阻力预先输入的可行性 ;各分支阻力的变化对通风系统的影响程度是不一样的 ,这由分支在通风网络中的位置决定 ;通过分析 ,给出了通风系统中两风机的相互影响的情况。     

南太湖地区小型浅水湖泊自净能力季节变化研究

以南太湖地区小型浅水湖泊为对象,研究了湖泊水体自净能力季节变化的特征.结果表明,湖泊对高锰酸盐指数、总氮(TN)、铵态氮(NH4+-N)、硝态氮(NO3--N)、总磷(TP)、叶绿素a(Chl-a)的净化能力季节性差异较大.各水质指标春季和冬季自净效果较好,夏季自净效果较差的是NH4+-N和NO3--N,秋季是TP和Chl-a.湖泊四季水体有机污染较轻,TN、TP污染严重.TN、TP浓度条件适宜藻类生长,水体容易发生富营养化,磷为限制性因子.Chl-a浓度显示湖泊在夏秋两季处于富营养化水平,冬春两季转变为中营养水平.浮游植物的生长与暴发对水质有较大影响,并影响到湖泊的自净能力.影响水体pH值和溶解氧(DO)浓度的主要因素是水生植物的种类和数量,农田肥料流失和农村生活污水排放是造成水体中氮磷含量过高的主要原因.过量使用有机肥使得夏季湖泊水体中有机氮占TN的主要部分,其他季节NO3--N占TN的主要部分.主成分分析结果表明,影响南太湖地区小型浅水湖泊自净能力的3个主成分分别为浮游植物因子(水温、pH、高锰酸盐指数和Chl-a)、农田排水因子(pH、DO和TN)和营养因子(TN和TP).聚类分析结果表明,3个湖泊11个采样点4个季节的水质可聚为两大类,春秋冬季为一类,夏季为一类,这一结果是受温度变化及农田排水所致.利用水温和pH拟合出用于计算湖泊水体中的高锰酸盐指数、TN、TP、Chl-a的线性方程,提高了现场快速预测能力.     

第二阶梯湖泊富营养化自然地理因素及效应

为了明晰影响我国地形地貌第二级阶梯湖泊富营养化的主要自然地理驱动因素,为湖泊富营养化的有效治理提供参考,采用曲线回归方法分析了位于我国第二级阶梯的云南和新疆湖泊中Chl-a以及营养状态综合指数(TLI)与自然地理特征的相关性.结果表明,平均水深、海拔以及年均温与TLI指数具有较好的相关性,拟合模型分别符合三次/对数模型、二次模型和三次模型.Chl-a与年平均日照时数具有较好的相关性,拟合模型符合二次/三次模型.分析富营养化效应,藻类生长对透明度的影响以及营养物质对浮游藻类的生态效应(Chl-a/TP),结果发现,新疆湖泊中Chl-a与透明度呈倒数关系,云南湖泊中Chl-a与透明度呈幂函数关系;Chl-a与总磷的线性方程的斜率分别为177.595(云南)和222.758(新疆).影响我国第二级阶梯湖泊富营养化的主要自然地理驱动因素是湖泊的平均水深、海拔、年均温度及年平均日照时数,透明度与Chl-a含量的相关性以及营养物质TP对浮游藻类的生态效应存在区域差异.     

GM（1， 1）正弦模型修补气温监测缺失数据的探讨

目的建立预测精度较好的大气温度监测缺失数据修补的方法和模型。方法采用正弦函数对GM(1,1)标准模型进行修正,建立分段的GM(1,1)正弦修正模型对缺失数据进行修补。以万宁试验站某天监测的温度日记时值数据为试验数据,同时建立GM(1,1)标准模型、GM(1,1)时序修正模型和GM(1,1)正弦修正模型,对比分析各模型的修补误差,确立较好的修补模型。结果从模型的拟合效果分析,GM(1,1)标准模型和GM(1,1)正弦修正模型的拟合性最好,GM(1,1)时序修正模型的拟合性相对较差一些;从预测精度上分析,GM(1,1)标准模型和GM(1,1)时序修正模型预测修补效果差,平均相对误差分别达到22.54%和17.70%,而GM(1,1)正弦修正模型预测修补的平均误差仅为3.14%,得到了较大的改进,预测效果好。结论正弦修正模型能很好地修补缺失数据,其修补效果比时序修正模型和标准模型都要好。     

Maximum likelihood fitting of the Poisson lognormal distribution

In this paper some properties and analytic expressions regarding the Poisson lognormal distribution such as moments, maximum likelihood function and related derivatives are discussed. The author provides a sharp approximation of the integrals related to the Poisson lognormal probabilities and analyzes the choice of the initial values in the fitting procedure. Based on these he describes a new procedure for carrying out the maximum likelihood fitting of the truncated Poisson lognormal distribution. The method and results are illustrated on real data. The computer program for calculations is freely available.

飞机铝合金结构腐蚀损伤预测方法对比性研究

依据飞机LD2结构材料的加速腐蚀试验数据,提出了数据拟合、神经网络、时间序列3种腐蚀损伤预测方法,并对3种预测方法的基本原理、预测精度及预测外延性进行了对比分析。研究发现神经网络和时间序列方法预测精度较高;时间序列方法的预测外延性较好,能够以较高精度预测未来一段时期腐蚀损伤的发展趋势及损伤程度。因此,应根据研究需要选用合适的方法进行腐蚀损伤预测。     

Testing of the Storm Water Management Model Low Impact Development Modules

Stormwater infrastructure designers and operators rely heavily on the United States Environmental Protection Agency’s Storm Water Management Model (SWMM) to simulate stormwater and wastewater infrastructure performance. Since its inception in the late 1970s, improvements and extensions have been tested and evaluated rigorously to verify the accuracy of the model. As a continuation of this progress, the main objective of this study was to quantify how accurately SWMM simulates the hydrologic activity of low impact development (LID) storm control measures. Model performance was evaluated by quantitatively comparing empirical data to model results using a multievent, multiobjective calibration method. The calibration methodology utilized the PEST software, a Parameter ESTimation tool, to determine unmeasured hydrologic parameters for SWMM’s LID modules. The calibrated LID modules’ Nash–Sutcliffe efficiencies averaged 0.81; average percent bias (PBIAS) ?9%; average ratio of root mean square error to standard deviation of measured values 0.485; average index of agreement 0.94; and the average volume error, simulated vs. observed, was +9%. SWMM accurately predicted the timing of peak flows, but usually underestimated their magnitudes by 10%. The average volume reduction, measured outflow volume divided by inflow volume, was 48%. We had more difficulty in calibrating one study, an infiltration trench, which identified a significant limitation of the current version of the SWMM LID module; it cannot simulate lateral exfiltration of water out of the storage layers of a LID storm control measure. This limitation is especially severe for a deep LIDs, such as infiltration trenches. Nevertheless, SWMM satisfactorily simulated the hydrologic performance of eight of the nine LID practices.