基于概率神经网络的城市湖泊生态系统健康评价研究

概率神经网络(PNN)是一种结构简单、训练简捷、应用十分广泛的人工神经网络,并且在水质分类等环境领域已取得一定研究成果.本文选取广州市最大的人工湖——白云湖作为研究对象,结合其水质监测数据及生物监测数据,建立概率神经网络模型对其进行湖泊生态系统健康评价,得到不同监测时间点的湖泊生态系统健康评价结果.分析表明:1白云湖生态系统比较脆弱,目前净化水质的效果有限;2各监测点的评价结果均呈季节性变化,丰水期湖泊生态系统健康状态好于枯水期,年际变化不显著.实验结果表明,利用概率神经网络对湖泊生态系统健康状态进行评价是可行的,与传统评价方法相比,其具有训练时间短、权重确定客观、输出结果稳定等优势,可以运用到更多相关领域.     

复三维电极-生物膜反应器脱除饮用水中硝酸盐的试验研究

研究了连续流复三维电极-生物膜反应器在不同电流、温度和pH条件下的反硝化性能.结果表明,在电流从0mA增加至100mA的过程中,NO3--N去除率随电流增大而升高;电流为100mA时NO3--N去除率最高,达到了73.8%,出水NO3--N浓度为8.27mg.L-1;电流高于100mA时,NO3--N去除率略有下降.电流从0mA增加至150mA的过程中,NO2--N积累量先增加后减少;电流为60mA时NO2--N的积累最为严重.温度为31～35℃时,反硝化效果较好,出水NO3--N浓度低于10mg.L-1;温度为35℃时,NO3--N去除率最高,达到了85.5%.pH值为7.2～8.2时,反硝化效果较为理想,出水NO3--N浓度在10mg.L-1以下,NO2--N浓度低于1mg.L-1.该反应器具有较好的pH缓冲性能,进水pH从5.5上升至9.0的过程中,其出水pH可维持在7.6～8.2,NO3--N去除率在59.6%～80.2%.此外,电流、温度和进水pH还对氨氮的生成量和总磷的去除产生明显影响.通过复三维电极-生物膜反应器与纯电化学反应器的对比试验,对氨氮产生和总磷去除的可能原因进行了分析和探讨.     

基于数值仿真-响应表面法的二沉池优化研究

以长沙市某污水处理厂二沉池为例,采用多相流混合物模型与k-ε湍流模型结合对辐流式二沉池内速度场和污泥浓度场进行了数值模拟.以出水口悬浮物浓度(SS)为响应目标,对影响二沉池沉淀效果的3个影响因素(进水口流速、颗粒污泥粒径、挡板的淹没深度)进行中心复合设计(central composite design,CCD),并经响应表面法分析得到影响出水SS的二次回归模型,确定了二沉池沉降的最佳条件:进水口流速为0.03m·s-1,颗粒污泥粒径为220.41μm,挡板的淹没深度为3.45m,采用数值仿真模拟实验得到出水口悬浮物浓度值为2.4mg·L-1,较优化之前的仿真结果一周平均值6.7mg·L-1相比,其处理效率提高了64.2%.采用数值仿真和响应表面法结合对二沉池工艺条件进行优化研究,可以加速寻优过程,是工艺优化的辅助工具.     

化肥厂尿素粉尘对人体的危害性调研及工业卫生评价

通过对动物皮肤染毒和皮下注射尿素溶液试验，观察尿素粉尘对动物皮肤、呼吸道和肝、肾等器官的损伤程度。对触尘人员与非触尘人员健康状况进行调查比较，分析尿素粉尘对人体的危害程度。结果：动物皮肤染毒４８小时后，对不同剂量染毒组的动物皮肤在光镜下观察试验结果，其表皮层细胞未见任何异常。对不同剂量染毒组经注射实验后，发现高浓度尿素粉尘对气管粘膜有轻度损伤，且有剂量——效应关系；在动物肝、肾、肺泡等器官未见明显损害。对触尘群体健康调查后，初步认为长时间接触尿素粉尘对人体呼吸系统有一定的影响，且局限在气管和支气管；尿素粉尘对人体皮肤基本无刺激作用。     

混沌理论在河流溶解氧预测中的应用初探

基于混沌理论、相空间重构思想和嵌入理论分析涟水流域溶解氧的时间序列，计算吸引子维数和最大的Lyapunov指数，研究河流水质系统的复杂性特征。结果表明，河流溶解氧时间序列具有混沌特性，其外在表现为貌似随机的无规则特点；但系统本身内在的、固有的规律(表现在最大的Lyapunov指数)，表明短期预测河流水质变化是可行的，并应用混沌相空间模线性回归模型进行了预测，其预测结果对涟水流域的水质管理和控制具有一定的参考价值。     

Effect of composting process on phytotoxicity and speciation of copper, zinc and lead in sewage sludge and swine manure

The concentration and bioavailability of heavy metals in composted organic wastes have negative environmental impacts following land application. Aerobic composting procedures were conducted to investigate the influences of selected parameters on heavy metal speciation and phytotoxicity. Results showed that both of sewage sludge (SSC) and swine manure (SMC) composting systems decreased the pH, the content of organic matter (OM) and dissolved organic carbon (DOC), and total amounts of Cu, Zn and Pb. Sequential extraction showed that readily extractible fractions of exchangeable and carbonate in Cu and Zn increased during SSC composting but decreased during SMC composting, thus their bioavailability factors (BF) enhanced in SSC but declined in SMC. The fraction of reducible iron and manganese (FeMnOX) of Cu and Zn in SSC and FeMnOX-Cu in SMC decreased, but FeMnOX-Zn in SMC gradually increased in the process of compost. In contrast, the changes of Pb distributions were similar in two organic wastes. Pb was preferentially bound to the residual fraction and its BF decreased. The evolution of heavy metal distributions and BF depended on not only total metal concentrations but also the other properties, such as pH, decomposition of OM and decline of DOC. The germination rate (RSG), root growth (RRG) and germination index (GI) of pakchoi (Brassica Chinensis L.) increased during the composting process. Linear regression analysis demonstrated that GI, which could represent phytotoxic behavior to the plants, could be poorly predicted by BF or total amount of metals, i.e., BF-Zn, T-Cu. However, the inclusion of other physicochemical parameters (pH, OM and DOC) could enhance the linear regression significances (R).     

洪水作用下汽车的起动流速研究

针对洪水作用下汽车的起动条件开展了一系列的研究:首先分析部分淹没状态下汽车的受力情况,结合滑动平衡的临界起动条件建立相关方程,导出了洪水中汽车起动流速公式;然后在室内水槽中对三款模型车进行了一系列的起动试验。试验结果表明:对于同一款模型车,平行于水流方向放置时,起动流速与水深的相关性较好;并且水深越大,起动流速越小。接着运用试验资料率定了起动流速公式中的相关参数。最后采用模型相似率及率定后的计算公式估算了原型车辆在不同水深下的起动流速,两种方法所得的结果较为接近,故预测结果较为可靠。     

不同火灾下建筑常用防火板材隔热性能试验研究∗

利用防火板材防护钢构件是钢结构防火的重要措施之一,而防火板材的隔热性能决定了钢结构的耐火性能, 为了研究建筑领域常用防火板材隔热性能,以及防火板材受火破坏形态和隔热性能随温度变化的规律,设计制作了 14 个防火板隔热性能试件,在三种火灾工况下对建筑领域常用防火板材进行隔热性能试验。研究结果表明：(1) 板材受火后的破坏形态和裂纹开展情况都与火灾升温历史有关;(2)板材受热过程中分解的结合水蒸发吸热是缓解钢板升温的重要影响因素之一;(3)用 ISO 834 标准升温下板材温度平台区域的 λ 取值结果来指导其他两种火灾情形下防火构造设计是安全的;(4)利用板材表面空气温度和钢板温度测试结果获得了板材导热系数,数值模拟计算与试验结果吻合良好,验证了采用导热系数测量方法的可靠性;(5)利用数值模拟与试验相结合的方法,分析得到石膏板的温度?等效导热系数简化曲线的两个重要敏感参数：热质传递影响温度区间等效导热系数结束变化的温度点(470 ℃)和该温度区间的等效导热系数波谷极值大小。     

Cathode ray tube (CRT) recycling: current capabilities in China and research progress

It is estimated that approximately 6,000,000 scrap TVs and 10,000,000 personal computers are generated each year in China. Cathode ray tubes (CRTs) from these machines consist of 85% glass (65% panel, 30% funnel and 5% neck glass). The leaded glass (funnel-24%, neck-30%) may seriously pollute the environment if it is not properly disposed of. In this paper, the past, current and future status of CRT dismantling technologies as well as the CRT glass recycling situation in China are presented and discussed. Recycling technology for waste CRTs in China is still immature. While the conventional CRT dismantling technologies have disadvantages from both economic and environmental viewpoints, some of the new and emerging treatments such as automatic optical sorting facilities that have been applied in developed countries offer advantages, and therefore should be transferred to China in the next few years to solve the CRT pre-processing problem. Meanwhile, because the demand for CRT glass closed-loop recycling is extremely limited, the authorities should take effective measures to improve CRT glass recycling rates and to facilitate a match to local conditions. Moreover, we also provide a broad review of the research developments in recycling techniques for CRT cullet. The challenge for the future is to transfer these environmentally friendly and energy-saving technologies into practice.     

基于分子信标探针的荧光定量PCR方法检测转基因食品

选择了内源基因大豆植物凝集素(lectin)、玉米转化酶(invertase)和外源基因花椰菜花叶病毒35S(CaMV35S)启动子的分子信标探针,确定了探针浓度和镁离子浓度等反应条件,分别对转基因大豆和转基因玉米系列标准品进行内源基因和外源基因的荧光PCR扩增,在PCR反应过程中分别以两种荧光通道信号分别追踪同一样品DNA内源基因和外源基因的扩增动力学变化,并依此绘制了循环阈值与转基因食品百分比含量之间的标准曲线,建立了转基因大豆和转基因玉米的分子信标探针-荧光定量PCR检测方法,该方法具有特异性强、敏感性高的特点,实现了对转基因食品的定量分析.图7表1参11