鼎湖山PM2.5中化学元素的组成及浓度特征和来源

为研究珠江三角洲大气颗粒物的污染特征及其来源,于2006年6～12月,在鼎湖山利用大流量颗粒物采样仪进行PM_2.5样品的采集,并利用ICP-MS分析其中的元素浓度.结果表明, Pb、V、Cu、As、Zn、Se元素平均浓度为216.24、 15.40、 60.56、 31.81、 432.06和8.12 ng·m^-3,处于高污染浓度水平.因子分析表明,化石燃料的燃烧、金属冶炼工业、扬尘和海盐是该地区PM_2.5的主要来源.     

活性污泥法对水溶性腐殖酸的去除效能与机制研究

采用人工配水的方式,研究了单级活性污泥法和两级活性污泥法对水溶性腐殖酸的去除效能,并通过测试污泥中腐殖酸的相对含量、污泥的元素组成、污泥的活性和进出水腐殖酸的分子量分布.对去除机制作了初步探讨.结果表明,在单级活性污泥处理系统中,不同浓度的腐殖酸均未对可生物降解有机物的去除构成影响,并且腐殖酸的去除率维持在67%-84%.随进水中腐殖酸浓度的增加去除率有所下降;通过两级活性污泥法试验.发现第l级活性污泥系统对腐殖酸的去除效果优于第2级.分别为71.3%和60.1%.且活性污泥系统对大分子量腐殖酸的去除效果优于小分子量腐殖酸.机制分析表明,腐殖酸难以作为微生物生长所需的碳源.主要依靠污泥吸附的方式,使水相中的腐殖酸进入泥相,再通过剩余污泥排放的方式去除.     

建筑荷载下桩-土作用机理与数值模拟

桩-土间相互作用机理的研究是保证桩基础在建筑荷载下安全稳定的关键。本文在分析建筑荷载下桩-土间相互作用机理的基础上,利用有限元分析软件对桩在建筑荷载作用下桩-土之间相互作用方式进行了有限元数值模拟研究,采用弹簧单元以及表面效应单元模拟土层对桩的作用力,建立了完整的桩-土作用模型,并得到了在建筑荷载和土层作用力下桩的位移量及其轴向应力分布。该研究可为建筑基础设计提供理论依据。     

基于构造应变对隧道初始地应力场的反演分析

岩体中的初始地应力场是岩体稳定性与工程运营必须考虑的重要因素。以东营子隧道工程为例,以隧址区构造应变作为待求解的约束条件,结合工程地质条件和实测地应力资料,运用有限元软件对隧址区地应力场进行了回归反演分析。结果表明:基于区域构造应变获得的隧址区初始应力场克服了边界条件对地应力场的影响,更加准确地反映了隧址区地应力场的分布规律,可为隧道围岩稳定性分析提供准确的位移边界条件。     

考虑液固耦合储液罐非线性地震反应分析

利用ADINA有限元软件研究了考虑液固耦合的立式圆筒形锚固储液罐非线性地震反应.通过分析计算1000m3储液罐自振特性,储液罐的加速度峰值沿罐壁高度变化趋势,罐壁的应力分布等反应,初步揭示其破坏机理,分析结果为储液罐的抗震设计提供重要的参考依据.     

Analysis of risk trade-off relationships between organic solvents and aqueous agents: case study of metal cleaning processes

When substance substitution is implemented to reduce the target risk of production processes, countervailing risks may occur. The goal of this study is to analyze the risk trade-off relationships between organic solvents and aqueous agents in the case study of metal cleaning processes. Global environmental impacts and local risks were evaluated for the eight scenarios by life cycle and risk assessments, respectively. The results show that the contribution of the processes using chlorinated solvents to photochemical ozone creation, human toxicity, ozone depletion, and ecotoxicity was larger than processes using aqueous detergents, while the contribution of aqueous processes to eutrophication was larger than chlorinated processes. Neighbors’ health risk around a cleaning site using chlorinated solvents was sufficiently small in all scenarios, whereas ecological risk due to surfactants which are contained in aqueous detergents and emitted to the local aquatic environment should be reduced. Cleansing agents and process facilities should be selected on the basis of the comprehensive analysis of risk trade-off relationships for feasible and cleaner production.     

炼油装置元素S高温腐蚀产物FeS2的自然氧化性

使Fe2O3和Fe(OH)3分别与元素S在不同条件下进行硫化反应,并采用X射线衍射仪鉴定硫化产物组成,在95 ℃恒温水浴中对硫化产物进行氧化反应,考察了硫化温度和硫化时间对硫化产物自然氧化性的影响.结果表明,元素S高温硫化产物主要是FeS2.硫化产物FeS2具有较高的自然氧化性,随着硫化温度升高,硫化时间延长,硫化产物的自然氧化性增大,更容易发生氧化放热反应,造成油品火灾和爆炸事故.元素S与Fe2O3硫化温度在360 ℃以上,与Fe(OH)3硫化温度在300 ℃以上时,其硫化产物FeS2具有较高的自然氧化性.硫化时间在24 h以上时,Fe2O3、Fe(OH)3的硫化产物自然氧化性较大.     

Sensitivity of Head and Cervical Spine Injury Measures to Impact Factors Relevant to Rollover Crashes

Objective: Serious head and cervical spine injuries have been shown to occur mostly independent of one another in pure rollover crashes. In an attempt to define a dynamic rollover crash test protocol that can replicate serious injuries to the head and cervical spine, it is important to understand the conditions that are likely to produce serious injuries to these 2 body regions. The objective of this research is to analyze the effect that impact factors relevant to a rollover crash have on the injury metrics of the head and cervical spine, with a specific interest in the differentiation between independent injuries and those that are predicted to occur concomitantly.

Methods: A series of head impacts was simulated using a detailed finite element model of the human body, the Total HUman Model for Safety (THUMS), in which the impactor velocity, displacement, and direction were varied. The performance of the model was assessed against available experimental tests performed under comparable conditions. Indirect, kinematic-based, and direct, tissue-level, injury metrics were used to assess the likelihood of serious injuries to the head and cervical spine.

Results: The performance of the THUMS head and spine in reconstructed experimental impacts compared well to reported values. All impact factors were significantly associated with injury measures for both the head and cervical spine. Increases in impact velocity and displacement resulted in increases in nearly all injury measures, whereas impactor orientation had opposite effects on brain and cervical spine injury metrics. The greatest cervical spine injury measures were recorded in an impact with a 15° anterior orientation. The greatest brain injury measures occurred when the impactor was at its maximum (45°) angle.

Conclusions: The overall kinetic and kinematic response of the THUMS head and cervical spine in reconstructed experiment conditions compare well with reported values, although the occurrence of fractures was overpredicted. The trends in predicted head and cervical spine injury measures were analyzed for 90 simulated impact conditions. Impactor orientation was the only factor that could potentially explain the isolated nature of serious head and spine injuries under rollover crash conditions. The opposing trends of injury measures for the brain and cervical spine indicate that it is unlikely to reproduce the injuries simultaneously in a dynamic rollover test.     

滇东南岩溶区土壤有效态微量元素丰度特征及其影响因素

为了解滇东南岩溶区土壤有效态微量元素丰度特征及其影响因素,采用对角线取样法对研究区土壤进行采样并进行了测试分析.结果表明,不同地层土壤有效硼质量比由小到大为奥陶系、泥盆系、寒武系,有效铜质量比由小到大为寒武系、奥陶系、泥盆系,有效锌和有效铁质量比由小到大为寒武系、泥盆系、奥陶系.pH值、有机质是影响土壤有效态微量元素的重要因素,有效硼、有效铜、有效锌质量比与pH值呈正相关,有效铁质量比与pH值呈负相关;有效硼、有效铜质量比与有机质质量比呈极显著正相关(p＜0.01),有效锌质量比与有机质质量比呈显著正相关(p＜0.01),而有效铁质量比与有机质质量比相关性不明显.根据中科院微量元素组制定的标准,不同地层土壤有效硼、有效锌质量比级别为极低或低,有效铜质量比级别为中,有效铁质量比为高或极高.     

埋地热油管道泄漏裂纹开裂的应力研究

研究了导致埋地热油管道泄漏裂纹开裂的应力机制,采用有限元方法对埋地热油管道进行模拟计算,求得热-结构耦合作用下管道整体当量应力变化云图,并得出管道弯管处应力高于直管段应力的结论;继而采用电阻应变测试法对埋地热油管道的弯管处进行实时应力测定,并绘制了各测点的轴向和周向应力变化曲线,通过各测点应力比较得出弯管内侧有两点应力波动幅值偏大,弯管外侧4号测点处轴向应力超过管材的屈服点。结果表明:在结构-热应力耦合作用下,埋地热油管道在弯管外侧轴向应力最大,易有I型裂纹萌生并扩展,在弯管内侧易有疲劳裂纹萌生并扩展。