多介质潜流人工湿地的水动力过程模拟

水动力过程是湿地净化功能发挥的重要机制之一.根据脉冲示踪试验,获得潜流人工湿地的水力停留时间分布曲线.针对其"多峰"现象,利用数学软件MATLAB7.0分别将对数正态分布、对流扩散模型以及考虑延迟的连续完全混合反应器模型时脉冲示踪试验数据进行叠加模拟,同时利用多流弥散模型拟合分析,结果表明:叠加模型和多流弥散模型均能较...     

沙尘暴期间上海市大气颗粒物元素地球化学特征及其物源示踪意义

采集了2009年10月～2010年10月上海市普陀、闵行、青浦这3个区的大气颗粒物(包括沙尘暴期间),并在南通、郑州、西安、北京等沙尘暴输沙沿途城市追踪采集春季大气颗粒物样品,运用XRF及ICP-MS分别测试了样品的主量及稀土元素含量.闵行、普陀、青浦区这3个区的大气颗粒物的化学组成非常相似,表明样品物源相似.将主量元素数据UCC标准化显示,沙尘暴样品主量元素含量较非沙尘暴样品更接近于黄土,可能主要来源于西北内陆地区,部分为局地源物质.北方各城市沙尘暴样品的稀土元素配分模式一致,且与黄土相似,说明沙尘暴样品物质来源与黄土接近,以壳源物质为主,说明非沙尘暴样品与沙尘暴样品和黄土物质来源不同,有非壳源物质的混合.     

Kelvin–Helmholtz Instability as a Boundary-Value Problem

The Kelvin–Helmholtz (KH) instability is traditionally viewed as an initial-value problem, wherein wave perturbations of a two-layer shear flow grow over time into billows and eventually generate vertical mixing. Yet, the instability can also be viewed as a boundary-value problem. In such a framework, there exists an upstream condition where a lighter fluid flows over a denser fluid, wave perturbations grow downstream to eventually overturn some distance away from the point of origin. As the reverse of the traditional problem, this flow is periodic in time and exhibits instability in space. A natural application is the mixing of a warmer river emptying into a colder lake or reservoir, or the salt-wedge estuary. This study of the KH instability from the perspective of a boundary-value problem is divided into two parts. Firstly, the instability theory is conducted with a real frequency and complex horizontal wavenumber, and the main result is that the critical wavelength at the instability threshold is longer in the boundary-value than in the initial-value situation. Secondly, mass, momentum and energy budgets are performed between the upstream, unmixed state on one side, and the downstream, mixed state on the other, to determine under which condition mixing is energetically possible. Cases with a rigid lid and free surface are treated separately. And, although the algebra is somewhat complicated, both end results are identical to the criterion for complete mixing in the initial-value problem.     

The Austrian P budget as a basis for resource optimization

Phosphorus (P) is a finite and non-substitutable resource that is essential to sustaining high levels of agricultural productivity but is also responsible for environmental problems, e.g., eutrophication. Based on the methodology of Material Flow Analysis, this study attempts to quantify all relevant flows and stocks of phosphorus (P) in Austria, with a special focus on waste and wastewater management. The system is modeled with the software STAN, which considers data uncertainty and applies data reconciliation and error propagation. The main novelty of this work lies in the high level of detail at which flows and stocks have been quantified to achieve a deeper understanding of the system and to provide a sound basis for the evaluation of various management options. The budget confirms on the one hand the dependence of mineral P fertilizer application (2 kg cap⁻¹ yr⁻¹), but it highlights on the other hand considerable unexploited potential for improvement. For example, municipal sewage sludge (0.75 kg cap⁻¹ yr⁻¹) and meat and bone meal (0.65 kg cap⁻¹ yr⁻¹) could potentially substitute 70% of the total applied mineral P fertilizers. However, recycling rates are low for several P flows (e.g., 27% of municipal sewage sludge; 3% of meat and bone meal). Therefore, Austria is building up a remarkable P stock (2.1 kg P cap⁻¹ yr⁻¹), mainly due to accumulation in landfills (1.1 kg P cap⁻¹ yr⁻¹) and agricultural soils (0.48 kg P cap⁻¹ yr⁻¹).     

用于处理含油废水的吸油罐的研制

聚丙烯纤维是一种很好的吸油材料 ,以它作为吸油罐内的滤料吸附含油废水中的油 ,使水达标排放 ,再用蒸汽吹扫滤料上的油进行收集 ,使油回收利用     

微环境新风量的检测原理及方法研究

新风量是评价室内微环境空气卫生质量的主要卫生指标之一,也是计算室内某种气体单位时间排放量的重要参数。以CO2作为示踪气体,利用于冰升华和人体呼吸产生CO2示踪气体两种测量方法对室内和车内微环境进行了检测,并考虑室内人呼出CO2量的影响,运用箱子模式的各种推导公式（稳态法、解析解法和差分法）对新风量进行了计算,并对结果进行了讨论。结果表明,没有人存在下,用箱子模式的解析解法和差分法计算的新风量值没有明显的统计差异;微环境内有人时必须考虑人释放的影响,这样箱子模式的各种推导公式都可以计算新风量值,且结果准确,准确度高。利用人体呼吸产生CO2示踪气体法,用差分法计算结果不理想,偏差很大;用稳态法计算重现性高,结果可靠。     

潮汐流人工湿地的除氮效果及影响因素

为研究TF-CW(tidal flow constructed wetland,潮汐流人工湿地)的除氮效果及其主要影响因素,以连续流模拟装置(A组)为对照,设置3种潮汐进水方式〔RAT(闲置时间∶反应时间)分别为1∶1、1∶2、2∶1,依次记做B组、C组、D组〕,运行175 d,分析不同进水方式下TF-CW模拟装置对TN、NH₄+-N、NO₃--N、TOC的去除效果及其在不同处理深度上的变化. 结果表明:A、B、C、D组TN平均去除率分别为82.41%±4.84%、84.82%±5.09%、86.09%±3.99%、90.23%±3.05%. A组TN和NH₄+-N的去除效果与B、C、D组均差异显著(P<0.05),其中D组TN和NH₄+-N的去除效果均最好;A组对NO₃--N的总体去除效果较优;RAT并不影响TOC的去除率. 不同进水方式下,NH₄+-N的去除率均在0~15 cm深度内最大,ρ(TOC)处于较低水平(0~20 mg/L),二者均随处理深度的不断增加而逐渐下降;ρ(NO₃--N)在0~15 cm深度内迅速上升. 随着闲置时间的增加,ρ(DO)逐渐升高. TN和NH₄+-N的去除率随着运行时间的增加基本保持恒定,主要影响因子有ρ(DO)、RAT、ORP(oxidation reduction potential,氧化还原电位)和ρ(TOC);而NO₃--N的去除率随着运行时间的增加而逐渐降低,其主要影响因子有pH、电导率和水温等.      

提高装备自身防护能力抵御自然环境侵蚀

简述自然环境对飞机装备的影响,针对提高飞机自身防护能力方面提出了抵御自然环境侵蚀的对策,研制的飞机露天防护材料--931系列涂料,已广泛的应用于飞机装备的密封防护和封存等方面.     

基于栖息地模拟的重口裂腹鱼繁殖期适宜生态流量分析

介绍了栖息地模拟方法原理及步骤,以姜射坝水电站减水段为例,应用栖息地模拟模型PHABSIM计算了重口裂腹鱼繁殖期适宜生境需水量。结果表明,该河段内重口裂腹鱼繁殖期适宜生态流量为40.6m3/s,其与水文学法的结果对比表明,该流量可以满足维持水生生物良好的生存条件的要求。指出当工程河段涉及珍稀鱼类关键生境时,采用栖息地模拟法确定受影响河段的生态需水量,可以更好地保护珍稀鱼类关键生境。研究结果可为已建电站减水河段生态修复工作提供依据,为拟建电站水生生态环境影响评价工作提供借鉴。     

考虑期权采购的应急物资多种供应方式协调优化模型

突发事件的不确定性为灾后应急物资供应带来巨大挑战,而灾前政府难以控制相关应急物资的储备量及成本。实物储备、期权采购和市场化采购3种应急物资供应方式在灾前灾后应急物资保障具备各自的优势和弊端。仅靠单种物资供应方式难以权衡当前应急物资保障对经济性和时效性的要求,因此,需要将3种物资供应方式进行协调优化。对比3种供应方式在成本与效率方面的差异,利用期权采购弥补其他方式在成本和时效方面的不足,将3种物资采购方式协调整合。以政府和供应商双方签订期权契约为前提建立多种采购方式协调优化模型,通过优化算法求解模型。最后通过算例分析验证得出结论。研究结果表明:存在基于期权采购的多种采购方式并存的应急物资保障机制,可使应急物资供应的成本和效率得以权衡。