Analytical solutions of three-dimensional contaminant transport in uniform flow field in porous media: A library

The purpose of this study is to present a library of analytical solutions for the three-dimensional contaminant transport in uniform flow field in porous media with the first-order decay, linear sorption, and zero-order production. The library is constructed using Green’s function method (GFM) in combination with available solutions. The library covers a wide range of solutions for various conditions. The aquifer can be vertically finite, semi-infinitive or infinitive, and laterally semi-infinitive or infinitive. The geometry of the sources can be of point, line, plane or volumetric body; and the source release can be continuous, instantaneous, or by following a given function over time. Dimensionless forms of the solutions are also proposed. A computer code FlowCAS is developed to calculate the solutions. Calculated results demonstrate the correctness of the presented solutions. The library is widely applicable to solve contaminant transport problems of one- or multiple- dimensions in uniform flow fields.     

基于覆盖水量的监测点优化选址法的缺陷与改进

研究了给水管网水质监测点选址的方法,分析了覆盖水量法存在的缺陷,针对这一缺陷,提出了一种基于覆盖水量指数的改进方法,在评价节点的代表性时,该方法同时考虑了总覆盖水量和覆盖水量时间分布对节点代表性的影响,提高了管网水质监测点优化选择的准确度和监测数据的代表性.为了提高优化问题求解的速度,采用了遗传算法求解水质监测点优化选址问题,并将此两类方法应用于2个案例管网.对于案例中的管网,采用布设7个监测点,可有效监控所有95个节点中85%以上的管网水量.同时,实际案例管网的应用表明,与覆盖水量法相比,覆盖水量指数法的计算结果具有更好的代表性,基于此建立的给水管网在线监测网络能够更好地代表管网的水质情况.     

不同沉水植物对Cu，Pb，Cd，Zn元素吸收积累差异及规律研究

为探求不同种类的沉水植物对水中Cu,Pb,Cd,Zn吸收积累的差异.对生长在广西刁江流域中的几种常见的沉水植物:菹草、黑藻、狐尾藻、苦草、黄丝草进行了分析,结果表明:在不同采样点与不同时期里.Cu.Pb,Cd,Zn元素在同一沉水植物中吸收变化比较大,Zn元素含量在被测元素中变化最大,最高值和最低值差约581倍.这说明沉水植物受环境影响比较大,能较好的反应出周围环境的变化;但不同的沉水植物对周围环境反应能力的大小是不一样的,菹草、黑藻、狐尾藻、苦草、黄丝草对Cu,Cd,Zn重金属元素的富集能力顺序依次为:菹草>黑藻>狐尾藻>苦草>黄丝草;而黄丝草对Pb吸收累积能力在所有被检测沉水植物中富集能力是最强的.因此,我们在利用沉水植物来指示或修复水体环境时,必须依据不同的元素来选择合适的沉水植物.     

地震灾害下城市供水网络韧性评估及优化研究

为提升城市供水网络应对地震灾害的能力,基于性能响应函数(PRF)方法,引入基础设施网络均衡理论,设计综合考虑城市供水网络物理状态和输送能力的性能时程响应函数,构建贯穿结构和功能双维度的地震灾害下城市供水网络韧性评估方法;从灾害概率、灾害后果、恢复速度、恢复程度等4个关键因素出发,提出城市供水网络网状扩张、管道延性改造、增加恢复资源和提升恢复储备等韧性优化策略;以我国华东某市供水网络为例,定量评估不同优化策略下的韧性提升效果,提出不同决策场景下恢复资源r和恢复储备b的优化配置方法。结果表明:管网延性改造是提升供水网络韧性的有效措施,网状扩张能提升供水网络性能,但对韧性提升无明显作用,网状扩张后要注意增加网络恢复资源和恢复储备。     

体育馆应急医疗功能转换的可行性评估*

为高效实现体育馆建筑的应急医疗功能转换,建立城市应急医疗体系,在探讨相关案例和体育馆建筑特点的基础上,提出在规划选址、室外空间、主体建筑、基础设施、应急响应能力5个方面建立体育馆应急医疗功能转换的可行性评估指标体系,并采用层次分析法确定各级指标的权重。以某市体育中心为例验证评估指标的合理性。结果表明:该评估指标体系能够合理反映城市体育馆应急医疗功能的差异,具有实用性和可操作性。     

复合型水雾抑尘剂作用机理与优选方法研究*

为有效提高水雾综合除尘性能,基于水雾捕尘过程及抑尘作用机理,从复合抑尘剂润湿、吸湿、黏结作用组分出发,讨论不同性质粉尘与抑尘剂各组分间匹配协同关系,进而研究复合型水雾抑尘剂优选方法。结果表明:湿润组分优选疏水端含有碳碳双键、醚基或链间存在氢键的表面活性剂;通过改变疏水基链长、不饱和度和支链数等方法,使湿润组分亲水、亲油性与粉尘相匹配。吸湿组分优选体心立方晶胞结构、溶解度相对较小的无机盐或混合配方无机盐,或者含极性强、能形成氢键的基团且空间结构复杂的有机吸湿剂。黏结组分优选溶液黏度高、交联网状、结构复杂的高分子聚合物。在上述组分优选的基础上,通过抑尘剂复配性能实验合理确定各组分的最优配比。     

基于半定量的FRAM道路危险品运输事故分析方法研究*

为弥补事故分析法在道路危险品运输事故致因研究方面的缺失,解决传统事故分析方法分析结果不全面、防控措施不具体且针对性较差的问题,引入半定量功能共振事故模型（FRAM）,通过定量化功能上下游耦合变异性,阐述事故发生机理同时,找到系统关键功能和关键链路,制定防控措施重点监控。结果表明:基于半定量的FRAM道路危险品运输事故分析方法能够更快、更准确地找出事故发生的关键功能和关键链路,制定针对性防控措施,有效提高道路危险品运输系统安全性。研究结果可为道路事故分析提供参考。     

西安市冬季大气颗粒物中多环芳烃的分布特征

对西安市不同功能区大气颗粒物中13种优控多环芳烃(PAHs)的研究表明,西安市冬季大气颗粒物中PAHs污染严重,各采样点13种PAHs总浓度(∑PAHs)为121.61～302.25 ng/m3,平均浓度为188.44 ng/m3,其中强致癌的苯并[a]芘(BaP)平均浓度为12.63 ng/m3;不同功能区大气颗粒物中PAHs和BaP的浓度分布存在明显差异,∑PAHs浓度依次为:交通繁忙区＞学生公寓(燃煤排放明显)＞农业开发区＞高新产业开发区＞商业区＞校园,BaP浓度:交通稠密区＞农业开发区＞环工学院(学校教师的停车场)＞商业区＞学生公寓＞高新产业开发区;不同功能区大气颗粒物中,中高环PAHs含量占优势,不同环数PAHs占总量的比例顺序为4环(38.64%)＞5环(25.17%)＞6环(18.83%)＞3环(10.25%).     

基于马尔萨斯模型对钢铁企业伤害事故与工龄指数之间规律的研究

为了验证在钢铁企业中人的失效过程同服役年限有某种规律性的联系,采用马尔萨斯模型对人的服役年限--工龄与伤害事故频数之间的规律性进行机理推证.在对典型钢铁企业40年间工伤事故数据库中的1 465起伤害事故进行统计分析、建立回归模型后,结论显示伤害事故频数y与受害人员的本工种工龄x存在显著指数相关关系:y=167.13e0.012x、相关系数R=0.93,证实了马尔萨斯模型应用于"工龄-伤害事故频数"指数规律的准确性.改进后的指数规律模型对实际钢铁企业安全管理工作有着重要的研究价值和指导意义,且可以在其他领域中进行探索和推广.     

Positive long-term effect of mulching on species and functional trait diversity in a nutrient-poor mountain meadow in Central Europe

Oligotrophic mountain meadows are threatened biodiversity hotspots throughout Europe. The traditional summer hay-making followed by autumn grazing is no longer economic and question is whether alternative managements can maintain both plant species and functional diversity typical of these habitats. In the Bohemian Forest Mts., we applied three treatments (mowing once a year - i.e., cutting and removing the biomass, mulching once a year - cutting and leaving the crushed biomass to decompose in situ, fallowing - no cutting) in order to assess temporal changes in meadow vegetation, plant trait composition and biomass production in a 13-year experiment. We recorded for each species twenty-five traits as to be most informative of plant strategies related to growth, resource acquisition and carbon-water economy. We compared different components of trait composition (community averages that mostly reflect traits of dominant species vs. the Rao index of functional diversity that reflects trait dissimilarity among species) and their impact on biomass production. We show that mulching promotes species and functional diversity by facilitating heliophilous forbs and legumes with more acquisitive strategies in resource use and release, e.g., higher foliar N and P content. This occurs at the expense of tall grasses (with resource-retentive strategies, e.g., high leaf dry matter content) which dominate the mown and fallow plots. The divergence in most quantitative traits indicates that niche complementarity is the dominant assembly process in mulched plots, which can prevent competitive exclusion and enable species coexistence. The divergent development was detected only after 5-6 years. This slow floristic and functional response is caused by acidity of soil and severe mountain climate that preclude rapid responses of vegetation to land-use changes. We conclude that mulching represents a good compromise maintaining both plant species and functional diversity as well as a relatively high biomass production. Mowing without grazing leads to gradual nutrient loss and thus reduces the productivity and diversity in these oligotrophic ecosystems. Fallowing causes gradual loss in diversity by increased grass competition and litter accumulation.