Progress in developing an ANN model for air pollution index forecast

An air pollution index (API) reporting system is introduced to selected cities of China for public communication on air quality data. Shanghai is the first city in China providing daily average API reports and forecasts. This paper describes the development of an artificial neural network (ANN) model for the API forecasting in Shanghai. It is a multiple layer perceptron (MLP) network, with meteorological forecasting data as the main input, to output the next day average API values. However, the initial version of the MLP model did not work well. To improve the model, a series of tests were conducted with respect to the training method and structure optimization. Based on the test results, the training algorithm was modified and a new model was built. The new model is now being used in Shanghai for API forecasting. Its performance is shown reasonably well in comparison with observation. The application of the old model was only weakly correlated with observation. In 1-year application, the correlation coefficients were 0.2314, 0.1022 and 0.1710 for TSP, SO₂ and NO_x, respectively. But for the new model, for over 8 months application, the correlation coefficients are raised to 0.6056, 0.6993 and 0.6300 for PM₁₀, SO₂, and NO₂. Further, the new algorithm does not rely on manpower intervention so that it is now being applied in several other Chinese cities with quite different meteorological conditions. The structure of the model and the application results are presented in this paper and also the problems to be further studied.     

农药污染地下水的微生物治理及含水层渗透性变化研究

采用了从农药厂阿特拉津生产车间排污口污泥中分离出的菌种AT菌 ,进行了农药阿特拉津污染地下水微生物治理的模拟实验研究 ,在实验条件 (T =10℃ ,pH =7.5 )与野外含水层的条件基本一致情况下 ,难于生物降解的污染质阿特拉津的一次投菌降解率可达 3 1.0 8% ;设计了两种有效细菌的投放方式以模拟野外条件下的菌种投加条件。另外 ,AT菌的作用会造成被治理含水层的渗透性能降低 ,两种投菌方式下 ,实验后含水层的渗透系数分别下降 60 .5 4%和 3 4 5 6%。清水冲洗 10d的渗透性恢复率分别为 48.96%及 81.3 6% ,说明清水渗透恢复的方法效果明显     

Human exposure and health risk of alpha-, beta-, gamma- and delta-hexachlorocyclohexane (HCHs) in Tianjin, China

The dynamic exposures to HCHs of individuals born between the years 1913 and 1993 in Tianjin have been simulated by connecting a fugacity model (IV) with a multimedia exposure model. Ingestion is the most important pathway for human beings to take up HCHs, and concentrations in the human body correlate with body weight changes. Accumulations of HCHs were derived assuming that the degradation in human body behaved linearly. The health risk of exposure to HCHs was measured using cancer risk and loss of life expectancy (LLE), and LLE was modified from its original definition to incorporate a dynamic calculation that takes variances in exposure into account. Monte-Carlo simulations were run to analyze the uncertainties of the model.     

悬浮颗粒物在河道滞留塘系统中的沉降与沉积特性

河道滞留塘系统是以颗粒物沉降为污染物主要净化机理的污染河流净化技术.通过1年的现场试验研究,考察了悬浮颗粒物SS在滞留塘中的沉降和沉积特性.在本试验条件下,随水力停留时间(HRT)延长(HRT为1.5～7 h),SS平均去除率逐渐增加,介于20%～40%之间,而SS去除速率则快速降低,SS去除速率与进水SS浓度成正比关系;不同季节河水中SS的沉降性能有较大差异,冬季河水中有机物含量较低的易沉降颗粒物比例较春秋季河水的为高,滞留塘HRT的选择应以去除易沉降颗粒物为标准,本研究条件下5 h以内是适宜的HRT选择范围.在滞留塘动态运行中,SS的沿程沉积量呈指数规律下降.     

Phosphorus fate and transport in soil columns loaded intermittently with influent of high phosphorus concentrations.

In this study, several columns of different lengths were filled with composite soils sampled from the field at corresponding depths and then loaded intermittently with influent of a high phosphorus concentration to evaluate phosphorus fate and transport in soil. The results indicate that the height of the mass transfer zone, solvent pore velocity, and soil's life expectancy for phosphorus removal increased with depth, while the retained phosphorus per kilogram of soil and the linear adsorption equilibrium coefficient, R, decreased with depth. An equation was developed to link liquid-phase phosphorus with solvent traveling time and soil depth. The results of X-ray diffraction and washout tests indicate that calcium-phosphorus precipitation and/or crystal growth occurred in the columns. The new protocol is useful for evaluation of phosphorus fate and transport in other subsurface systems, because it allows flexible adjustments in hydraulic loadings, feed solution, and sampling schemes.     

The organic precursors affecting the formation of disinfection by-products with chlorine dioxide

The object of this research was to study the formation of disinfection by-products by using chlorine dioxide (ClO2) as a disinfectant reacting with different properties of organic substance in natural aquatic environment. The adsorbent resin (XAD-4, XAD-7) was used to divide the organic matters in raw water into three groups. The influence of the function groups on structure, reaction tendency, and formation of disinfection by-products generated by the reaction of these organic substances with chlorine dioxide was explored. The experimental results show that the three different organic groups formed using adsorbent resin were hydrophobic substance, hydrophilic acid, and non-acid hydrophilics in proportions of 43%, 41%, and 16%, respectively. Within the raw water in our study, the hydrophilic substance had a higher distribution proportion than that described in general articles and journals, which indicates that this water was contaminated with pollution from human beings. The exploration of the reactivity of the three different organic substances with chlorine dioxide shows that the unit consumption of disinfection agent per unit organic matters (represented by ClO2/DOC) is in the following sequence hydrophobic substance > hydrophilic substance > non-acid hydrophilics. It indicated that larger molecular organic precursors had larger consumption of disinfectant. We also discovered that after the reaction of the three different organic substances with chlorine dioxide, the largest amount of disinfection by-products were generated by the non-acid hydrophilics.     

Longitudinal emissions evaluation of mixed (cooperative) adaptive cruise control traffic flow and its relationship with stability

ABSTRACT

Cooperative adaptive cruise control (CACC) vehicles need vehicle-to-vehicle (V2 V) communication to achieve CACC function. When a CACC vehicle follows a manual-driven vehicle (MDV) without V2 V communication, it needs degenerate to adaptive cruise control (ACC). By using real experiments, California PATH program indicated that ACC vehicles are apt to be unstable, which may have negative influence on fuel consumption and traffic emissions. Hence, this paper studies the impacts of the mixed CACC-MDV traffic on fuel consumption and emissions, by taking into consideration partial degenerations from stable CACC vehicles to unstable ACC vehicles. To deal with this, microscopic simulations were adopted by using car-following models. Then, an appropriate emission model was used for evaluating the emission impacts under different CACC market penetration rates (MPRs). In order to obtain reliable evaluation results, the models validated by PATH program using real experimental data were employed as the CACC and ACC car-following models. In addition, we also analytically investigated stability of the mixed traffic flow under different CACC MPRs, in order to explore its relationship with the emission impacts. The results show that the fuel consumption and emissions firstly increase and then decrease with the increase of the CACC MPR. This means the mixed traffic under some ranges of CACC MPRs will produce more fuel consumption and emissions, compared with the full MDVs traffic. It indicates that stability situations of the mixed traffic qualitatively influence the impact trend of CACC MPRs on fuel consumption and emissions. Then, V2 V communication equipments on MDVs are not only encouraging but also essential to avoid the deterioration of fuel consumption and emissions of the mixed traffic flow.     

中国国家公园建设潜在区域识别研究

国家公园是保护具有国家代表性资源的自然生态区域,建设国家公园体制是中国国土生态安全保障和生态文明体制改革的重要内容。论文基于国际经验、国家公园功能和政策内涵,依据国家公园主导定位和生态系统服务理念,构建了包含6个关键指标的综合评价模型,包括生态系统完整性、生态重要性、原真性、生物多样性、自然景观价值与人文遗产价值,分别进行单一要素层评价和多指标空间叠加分析,再结合中国生态地理区划、生态功能区划和省级行政区管理等因素进行比对和范围遴选提取,初步确定了中国国家公园建设的潜在区域。结果表明,生态系统完整性、生态重要性、生物多样性、原真性的高值集聚区域具有趋同性,生态系统完整性较好的区域,承担着重要的生态功能,生物多样性也较高,原真性保存较好。中国三大阶梯与自然地理区域的叠加分布特征明显,东西部潜在区域的面积差异较大,西部地区的空间连续性较强,潜在区域的跨界性较为明显。初步遴选出55处未来可以重点考虑建设的陆地型国家公园潜在区域。研究可为中国国家公园建设合理布局提供方法参考和理论借鉴。     

基于GIS格网化分析支撑的旅游空间规划技术方法研究——以青岛市为例

空间规划是支撑旅游地发展规划的核心章节,目前主要依靠规划者经验判断,主观性较强,缺乏客观方面的信息数据支持。论文将GIS格网化与旅游资源评价模型相结合,提出了旅游资源单体采集、旅游资源格网化及其空间分析方法,并融合旅游资源群评价模型、旅游功能区识别模型、旅游线路和空间发展轴线识别模型予以支撑,形成了标准化的旅游资源采集、评价到空间识别的集成技术方法;并以青岛市为例,识别出了旅游资源集群及其发展潜力、旅游功能区和空间拓展轴线,确立了“一心、一带、三轴、五区”的空间发展格局。论文初步探讨了GIS格网化空间分析方法在区域旅游规划中的应用,能够补充传统定性评价方法客观性不足的缺陷,实现复杂旅游资源数据的单体评价、旅游资源集群评价、旅游功能区识别、旅游线路和空间发展轴线优选的系列化分析技术路线,可为延伸旅游规划深度、提高规划精度提供科学参考。     

钢铁行业不同物料的二英生成分布及机理探讨

钢铁行业是我国二噁英的第一大排放源,但对不同钢铁生产过程二英的生成排放认识有所欠缺.本文系统探究了钢铁行业不同物料的二噁英生成能力和同系物分布特征.结果表明,烧结飞灰的二英生成能力最强,而烧结生料生成二噁英能力最弱.3种污泥(连铸、热轧、冷轧)和烧结生料的二英生成途径相似,4种飞灰(电炉、转炉、高炉一次、高炉二次)之间也有相似的二英生成途径,而烧结飞灰则与其他物料均不同.所有物料中,有毒2,3,7,8-PCDD同系物之间存在极强的相关性,且氯酚合成二噁英路径也被发现存在于钢铁生产过程中.