Comparison of UV-based advanced oxidation processes for the removal of different fractions of NOM from drinking water

This study examined the effectiveness for degradation of hydrophobic (HPO), transphilic (TPI) and hydrophilic (HPI) fractions of natural organic matter (NOM) during UV/H₂O₂, UV/TiO₂ and UV/K₂S₂O₈ (UV/PS) advanced oxidation processes (AOPs). The changing characteristics of NOM were evaluated by dissolved organic carbon (DOC), the specific UV absorbance (SUVA), trihalomethanes formation potential (THMFP), organic halogen adsorbable on activated carbon formation potential (AOXFP) and parallel factor analysis of excitation–emission matrices (PARAFAC-EEMs). In the three UV-based AOPs, HPI fraction with low molecular weight and aromaticity was more likely to degradate than HPO and TPI, and the removal efficiency of SUVA for HPO was much higher than TPI and HPI fraction. In terms of the specific THMFP of HPO, TPI and HPI, a reduction was achieved in the UV/H₂O₂ process, and the higest removal rate even reached to 83%. UV/TiO₂ and UV/PS processes can only decrease the specific THMFP of HPI. The specific AOXFP of HPO, TPI and HPI fractions were all able to be degraded by the three UV-based AOPs, and HPO content is more susceptible to decompose than TPI and HPI content. UV/H₂O₂ was found to be the most effective treatment for the removal of THMFP and AOXFP under given conditions. C1 (microbial or marine derived humic-like substances), C2 (terrestrially derived humic-like substances) and C3 (tryptophan-like proteins) fluorescent components of HPO fraction were fairly labile across the UV-based AOPs treatment. C3 of each fraction of NOM was the most resistant to degrade upon the UV-based AOPs. Results from this study may provide the prediction about the consequence of UV-based AOPs for the degradation of different fractions of NOM with varied characteristics.     

城市交通干线两侧机动车尾气污染状况分析

文中对PM10,SO2，NO2，CO四种污染因子，从时间、车流量、风力、气压、气温等方面进行影响分析，分析结果高浓度CO和NOx的污染出现在城市交通干道两侧和交通密集区域，上述四种污染园予在未来几年里仍然是环境空气中的主要污染物，危害城市人民正常生活的主要污染源，成为未来环境保护工作中的重点内容。     

南通市一次连续空气污染过程的气象特征分析

文章对2005年11月22日至12月2日南通市及邻近地区出现的大范围、长时间连续空气污染过程的天气形势和主要气象要素进行了分析。结果表明：大型稳定性高压伴随而来的稳定层结和小风速，导致大气污染物难于扩散，是这次空气污染过程的主要原因；弱冷空气无法改变大气稳定层结，难于结束空气污染状态；随着强冷空气到来，大气环流形势改变，空气质量改善。     

含半无限长裂纹压电材料的Ⅲ型强度因子

研究了含半无限长裂纹压电材料在平面内电场和反平面荷载作用下的问题 ,得到了满足拉普拉斯方程、裂纹面边界条件的位移函数解和电势函数解及电弹场的基本解 ,并得到了应力、应变、电位移强度因子和能量释放率。研究结果表明 ,在裂尖 ,电场强度没有奇异性 ,而应变、应力、电位移具有奇异性。     

人的安全性评价研究

随着人们对人在整个安全系统中的重要性认识的不断提高 ,如何对人的安全性进行科学的评价也就越来越显得重要。笔者在综合论述了目前我国对机车乘务人员、起重机械作业人员、驾驶员以及电力运行人员的安全性研究以及国外相关研究的基础上 ,提出了有关人的安全性评价的定义 ,并提出如何建立人的安全性评价体系以及对人的安全性评价的通用指标 ,探讨了在实际工作中如何运用上述指标去评价人的安全性。为人的安全性评价提供了一种有效的方法和新的研究思路     

生态小区特征和指标体系探讨

保护和建设生态小区，推行生态细胞工程是自然生态工作的有力补充。对于目前出现的许多生态小区，中国尚无一套正式通用的生态小区考评指标体系。本文从生态学的角度出发，探讨了生态小区的概念、内涵与其特征，并以此为基础，提出了生态小区的考评指标体系，希望以此引导四川省生态小区的创建活动。     

对Janbu普遍条分法计算方法的改进

Janbu普遍条分法(或称严格Janbu法)是第一个基于任意形状滑面且考虑滑体所有平衡条件的边坡稳定性计算方法。该方法存在的严重不收敛问题一直困扰着边坡理论和工程界近半个世纪。本文基于Janbu普遍条分法的基本原理和假设,重新推导出数学上更为简洁的安全系数积分表达式,指出传统计算格式不易收敛性是推力二阶导数的不合理数值误差所致,应用数值平滑技术可减少这个误差,使计算过程稳定收敛。研究表明,改进后的Janbu普遍条分法不失为理论相对严格、工程较为实用的边坡稳定性计算方法。     

四川省珙县地质灾害特征及其防治措施分析

本文从珙县地质灾害的分布特征、影响因素、防治措施等方面作了较为深入的分析和探讨，以期对地质灾害区划和防治有所借鉴和参考。     

岷江上游半干旱河谷土壤成土特征研究：以大沟流域为例

岷江上游半干旱河谷位于新构造运动活动带，其土壤形成和发育过程有着鲜明的区域特征。本文结合该区域的自然地理特点，综合分析各成土因素和土壤性状，对该区域土壤的成土特征进行了深入的分析和研究。     

Assessment of the maximum possible liquid superheat during flashing leak flow

During the discharge of flashing liquids through leaks due to abrupt depressurization a transient thermodynamic non-equilibrium in the form of a boiling delay in the superheated liquid flow can occur. As a consequence the actual mass flow quality is smaller than calculated under the assumption of an immediate adjustment of the thermodynamic equilibrium between the phases. For the prediction of the leak mass flow for a given pressure difference the magnitude of this self-adjusting mass flow quality is needed.

Most of the models cited in the literature include only the equilibrium mass quality as limiting quantity and ignore further effects as that of the depressurization velocity or the mean nucleus distance. For the assessment of the maximum possible liquid superheat during flashing only the conduction heat transfer from a stagnant liquid to the bubble surface is used to describe the bubble growth.

The sub-model for the bubble growth due to expansion and mass transfer necessary for the global prediction of the transient thermodynamic non-equilibrium in flashing liquids was validated using bubble radii measured by Hooper et al. [Bubble growth and pressure relationship in the flashing of superheated water. Technical publication 6904, Mechanical Engineering Department, University of Toronto, 1969] for the case of a sudden depressurization of initially saturated water. On this basis the calculated time-dependent temperature field, the actual mass quality, the mean liquid temperature and, in comparison to the corresponding values based on the assumption of immediate thermodynamic equilibrium, the maximum possible liquid superheat are predicted.