基于Logistic回归的燃气管网风险因素重要度分析方法研究

为确定燃气管网风险评估的关键风险因素,以A省各地市燃气管网为研究对象,基于燃气专家经验确定燃气管线风险等级,提出基于Logistic回归的燃气管网风险因素重要度分析方法。采用样本增强及随机抽样的方式,选取400个均衡样本作为管网评估数据输入,通过因子分析方法对其进行降维,得到3个公共因子并作为一级指标反向构建燃气管网风险评估指标体系;利用有序多分类Logistic回归方法,根据回归系数绝对值大小对风险因素进行重要度排序。研究结果表明：外界环境对燃气管网风险的贡献程度相对较高,管道自身因素和巡检养护次之。研究结果可为城市燃气风险防控提供理论依据和方法参考。     

Investigation of aerosol and gas emissions from a coal-fired power plant under various operating conditions

The concentrations of fine particles and selected gas pollutants in the flue gas entering the stack were measured under several common operation modes in an operating coal power plant producing electricity. Particle size distributions in a diameter range from 10 nm to 20 μm were measured by a scanning mobility particle sizer (SMPS), and the flue gas temperature and concentrations of CO₂ and SO₂ were monitored by a continuous emission monitoring system (CEMS). During the test campaign, five plant operating modes were studied: soot blowing, bypass of flue-gas desulfurization (FGD), reheat burner operating at 0% (turned off), 27%, and 42% (normal condition) of its full capacity. For wet and dry aerosols, the measured mode sizes were both around 40 nm, but remarkable differences were observed in the number concentrations (#/cm³, count per square centimeter). A prototype photoionizer enhanced electrostatic precipitator (ESP) showed improved removal efficiency of wet particles at voltages above +11.0 kV. Soot blowing and FGD bypass both increased the total particle number concentration in the flue gas. The temperature was slightly increased by the FGD bypass mode and varied significantly as the rating of reheat burner changed. The variations of CO₂ and SO₂ emissions showed correlations with the trend of total particle number concentration possibly due to the transitions between gas and particle phases. The results are useful in developing coal-fired power plant operation strategies to control fine particle emissions and developing amine-based CO₂ capture technologies without operating and environmental concerns associated with volatile amine emissions.

Implications: The measurement of the fine particle size distributions in the exhaust gas under several common operating conditions of a coal-fired power plant revealed different response relations between aerosol number concentration and the operating condition. A photo-ionizer enhanced ESP was demonstrated to capture fine particles with higher efficiency compared to conventional ESPs, and the removal efficiency increased with the applied voltage. The characteristic information of aerosols and main gaseous pollutants in the exhaust gas is extremely important for developing and deploying CO₂ scrubbers, whose amine emissions and operating effectiveness depends greatly on the upstream concentrations of fine particles, SO₂, from the power plant.     

过硫酸钾去除水中的TCE

以地水中的氯代烃污染物三氯乙烯(TCE)为目标污染物,以过硫酸钾溶液为氧化剂,探讨了不同条件下过硫酸钾对TCE的去除效果。实验结果表明,在40℃,过硫酸钾初始浓度为2.43 g/L条件下,反应2 h后,TCE的去除率就可达到96.8%;过硫酸钾对TCE的去除符合一级反应动力学方程,速率常数(K)为1.3364 h-1,半衰期(t1/2)为0.51 h;过硫酸钾对TCE的去除速率在pH为中性附近时最大,其后无论pH升高或降低去除速率均减小;受温度和pH影响较明显,并且反应温度越高,受pH的影响越明显;随离子强度的增加而减小;反应活化能为119.6 kJ/mol;过硫酸钾溶于水生成过硫酸根离子(S2O28-),S2O28-会进一步生成硫酸根自由基(SO4-.),在碱性条件下,SO4-.与OH-反应会进一步生成羟基自由基(.OH)。过硫酸钾对于TCE的去除主要源自SO4-.和.OH的强氧化性。     

Joint use of data and modeling in coastal wave transformation

In the framework of a research project entitled ??BRISA??BReaking waves and Induced SAnd transport??, a methodology was devised to characterize the waves joining together in-situ measurements and numerical wave propagation models. With this goal in mind, a number of in-situ measurements were made, for selected positions in front of Praia de Faro (South Portugal), during four days (25th to 28th March, 2009) by using different types of equipments (e.g., resistive wave gauges, pressure sensors, currentmeters and a new prototype pore pressure sensor using optical fibre). Wave records were obtained simultaneously offshore (at a water depth of 11.7?m below mean sea level, MSL) and at the surf and swash zones. The data processing and analysis were made by applying classical time domain techniques. Numerical simulations of the wave propagation between offshore and inshore for the measurement period were performed with two numerical models, a 1D model based on linear theory and a nonlinear Boussinesq-type model, COULWAVE, both forced by the measured offshore wave conditions of 27th March 2009. Comparisons between numerical results and field data for the pressure sensors placed in the surf and swash zones were made and discussed. This approach enables to evaluate the performance of those models to simulate those specific conditions, but also to validate the models by gaining confidence on their use in other conditions.     

The fungicide difenoconazole alters mRNA expression levels of human CYP3A4 in HepG2 cells

The fungicide difenoconazole has been frequently detected in agricultural products, soils and surface waters, causing increasingly public concern due to toxicological properties. Although systemic triazole fungicides can inhibit the enzymatic activity of many CYP450 isozymes, how difenoconazole affects the human CYP3A4 still remains largely unknown. We thus investigated the effect of difenoconazole on normal mRNA expression and protein expression of human CYP3A4 by real-time quantitative PCR and western blot, respectively. Results show that the exposure to difenoconazole from 0.01 to 0.5 μM for 24 h down-regulates mRNA expression levels of human CYP3A4 in HepG2 cells. We also found that difenoconazole could inhibit the enzymatic activity of human CYP3A4 in a concentration-dependent mode. The IC₅₀ of difenoconazole for inhibition of CYP3A4 activity is 0.41 µM, showing a stronger inhibitor in comparison with ketoconazole. Overall, our findings indicate the potential risk of difenoconazole for the disruption of human CYP3A4.     

底泥中多环芳烃(PAHs)提取方法评析

总结了底泥中多环芳烃(PAHs)提取的处理流程和国内外多种提取方法,比较了几种在我国较为常用的提取方法的效率.同时还提出了PAHs分离纯化的方法和步骤,并指出了提取过程中影响实验回收率的几个因素.     

基于SARIMA模型和普通Kriging法对杭州市主城区PM2.5短期预测和制图

基于SARIMA模型对杭州市主城区内的7个站点和周边3个站点的PM_(2.5)浓度进行4 h平均的短期预报,并利用普通Kriging法对杭州市主城区PM_(2.5)进行空间插值和制图.在建立SARIMA模型时,用批量自动化的方法,使用R语言编程对夏季和冬季各360期的数据进行SARIMA(p,d,q)×(P,D,Q)6模型的参数的确定和拟合,来预测下一期的值.在10个站点分别进行120期的预测,做出真实与预测的时间序列图,在精度分析中,夏季和冬季PM_(2.5)浓度总体的平均绝对误差(MAE)分别为8.4μg·m~(-3)和14.8μg·m~(-3).在Arc GIS中,对每期的数据使用普通Kriging法,用球面模型拟合半变异函数,决定各个站点的权重,来对杭州市区内未知空间样点进行插值,最后生成完整的杭州市主城区PM_(2.5)短期预测图.本研究创新性地将SARIMA模型广义化运用到小尺度时间序列中,预报效果较好,并且批量自动化预测和制图的方法,可为今后的预测制图产品化提供技术支持.     

厌氧折流板反应器处理石化剩余污泥

研究了厌氧折流板反应器(ABR)在厌氧消化处理石化剩余污泥启动过程中的性能及相关参数。实验结果表明:污泥挥发性固体含量的去除率达43.7%;反应器内pH维持在6.4~7.4;从启动到稳定运行,第一隔室最大比产甲烷活性变化不大,在0.14 L/(g·d)以下,第二、第三、第四隔室的最大比产甲烷活性在0.29 L/(g·d)以上,污泥在反应器内部实现了分级分相处理。     

Protecting the photosynthetic performance of snap bean under free air ozone exposure

Tropospheric ozone(O_3) is a major air pollutant and causes serious injury to vegetation. To protect sensitive plants from O_3 damage, several agrochemicals have been assessed,including cytokinin(e.g., kinetin, KIN) and ethylenediurea(EDU) with cytokinin-like activity.In higher plant, leaves are primarily injured by O_3 and protective agrochemicals are often applied by leaf spraying. To our knowledge, the mitigating abilities of EDU and KIN have not been compared directly in a realistic setup. In the present research, impacts of elevated O3(2 × ambient O_3, 24 hr per day, for 8 days) on an O_3 sensitive line(S156) of snap bean(Phaseolus vulgaris), which is often used for biomonitoring O_3 pollution, were studied in a free air controlled exposure system. The day before starting the O_3 exposure, plants were sprayed with a solution of EDU(300 ppm), KIN(1 mmol/L) or distilled water, to compare their protective abilities. The results demonstrated that 2 × ambient O_3 inhibited net photosynthetic rate and stomatal conductance, increased the minimal fluorescence yield of the dark-adapted state, decreased the maximal quantum yield of PSII photochemistry, and led to visible injury. KIN and EDU alleviated the reduction of the photosynthetic performance, and visible injury under O_3 fumigation. The plants sprayed with EDU showed greater ability to mitigate the O_3 damage than those sprayed with KIN. Chlorophyll fluorescence imaging may have detected more precisely the differences in O_3 response across the leaf than the conventional fluorometer.     

餐厨垃圾混菌发酵制备燃料乙醇

以校园餐厨垃圾为原料,利用根霉和枯草芽胞杆菌进行糖化预处理,再接种啤酒酵母发酵产乙醇。通过单因素实验,以乙醇产量为响应值,对发酵条件进行优化。实验结果表明:乙醇产量最佳的发酵条件为:当底料含水率为22.79%,啤酒酵母接种量为15%,30℃培养条件下,经过5 d发酵,乙醇产量最高可达到6.67%。选用餐厨垃圾丰富了燃料乙醇的取材途径,实现了原材料的多元化,采用微生物预降解原材料为实现高产乙醇奠定了基础。