可沉微藻对室外光照强度的适应性试验研究

在实验室条件下,通过"冲淘"压力可筛选出沉淀率高达97%的可沉微藻。可沉微藻像活性污泥一样在净化功能完成后可通过自然沉降实现藻-水分离,可为污水深度处理提供一种低耗、高效的解决方案。然而,实验室低光照[400μmol/(m²·s)]条件下获得的可沉微藻在真实自然光强度下是否依然可以不断生长繁殖并保持对氮、磷较高的去除率,这是一个工程应用必须面对的现实问题。为此,在实验室条件下增加光照强度至接近自然光水平[800μmol/(m²·s)],观察可沉微藻的生长情况。结果显示,高光照强度对可沉微藻具有抑制作用,使可沉微藻的生长繁殖严重受阻,并降低其光合作用活性(叶绿素a含量)。及时向反应器补充无机碳源CO₂后,可沉微藻经过一定适应期后可恢复生长,并可达到比低光照强度时还高的生物量及较高的氮、磷去除效果(90%以上)。另外,试验还考察了投加营养物硅酸盐、光/暗交替及进水模式对可沉微藻生长与净化性能的影响,结果显示出硅酸盐的双向性作用及光补充基质的优势。     

基于静力触探的液化势概率估计和判别标准

应用人工神经网络模型和可靠度理论 ,对大量液化和未液化场地的静力触探测量数据进行了分析 ,得到地震时饱和砂类土的极限状态函数和失效概率函数。以这两个函数为基础 ,给出液化势的概率估计方法 ,并结合我国建筑抗震设计规范有关设计地震分组的规定 ,提出了一般工程的具有明确概率的CPT液化判别标准。     

液化势的概率估计和判别标准

利用人工神经元网络模型和可靠度理论,对大量的液化和未液化场地标准贯入试验基本数据进行了分析,给出了地震时饱和砂土的极限状态函数和失效概率函数。对于重大工程可以利用这两个函数来确定场地的液化概率,并进行液化风险设计决策。但对于一般工程,通常是根据液化判别标准来估计其液化势。本文将提出一个新的建立液化判别标准的方法,根据这个途径并考虑我国建筑抗震规范中设计地震分组的有关规定,就一般工程场址给出具有明确概率的液化判别标准。这个途径与通常的方法相比,其优点是非常明显的。     

Potential of extension workshops to change farmers' knowledge and awareness of IPM

Farmers' knowledge of IPM has been considered, as prerequisites to IPM adoption. In Iran the most prevalent extension method for training farmers in different fields like IPM is extension workshops. The main purpose of this study was to investigate workshop effectiveness to change farmer's knowledge of IPM through assessing and comparing farmer's knowledge of IPM. A survey was conducted among 90 farmers in Karaj City in 2007-08 that included 30 workshop participants, 30 farmers who had exposed to workshop participants, and 30 randomly selected farmers, which were outside of this community. A questionnaire including open and close ended questions was designed. Data was collected through personal structured interviews with respondents at their farms. The study found that workshop participants (10.38) had significantly higher knowledge scores than their non workshop counterparts (5.90). Data also showed very little diffusion of workshop-acquired knowledge from workshop participants to other community members.     

碳纤维布加固钢筋混凝土连续梁受弯性能研究

通过5根连续梁的试验研究了碳纤维加固T形截面钢筋混凝土连续梁的受弯性能。研究结果表明, 在初始荷载小于极限承载力20%的情况下,可以忽略二次受力的影响。增加碳纤维粘贴层数对连续梁屈服荷 载影响较小,但极限承载力有一定提高。增加支座配筋率能有效提高支座及跨中的屈服荷载,但极限荷载并 无提高。采用改进后的“虚梁法”公式对屈服荷载和极限荷载进行分析,计算结果与试验荷载吻合较好。     

Identifying the sources and fate of anthropogenically impacted dissolved organic matter (DOM) in urbanized rivers

Anthropogenic activities have dramatically changed the loads and compositions of dissolved organic matter (DOM) in urbanized streams. In this study, the spatial and temporal variations of DOM in the anthropogenically impacted Zhujiang River were investigated by analyzing the water samples in an upstream, urbanized area and downstream of the rivers on different days of one year. The results indicated that the levels of dissolved organic carbon (DOC) and total phosphorus (TP) were unaffected by seasonal changes, but the specific UV₂₅₄ absorbance (SUVA) values and the total nitrogen (TN) content were greater in the winter than those in the summer. Parallel factor (PARAFAC) analysis of the excitation emission matrices (EEM) revealed the presence of three anthropogenically derived components [tryptophan-like (C1) and tyrosine-like proteins (C3) and anthropogenic humic substances (C5)] in the urbanized rivers, and they had greater seasonal and spatial variability than the terrestrial and microbial humic substances (C2 and C4). Cluster analysis revealed that treated wastewater was an important source of DOM in the urbanized streams. Photodegradation experiments indicated that the DOM in the populous area of the rivers had greater photodegradation potentials than that in the downstream region or in the natural waters. Interestingly, that the anthropogenic humic substances (C5) were considerably more photoreactive than the other four PARAFAC components, which exhibited a decrease of 80% after exposure to sunlight for 0.5 d. This study suggests that the treated wastewater could be an important input to the DOM in the urbanized rivers and the naturally occurring photodegradation could help in eliminating the anthropogenic DOM during their transport.     

Decolourization performance and mechanism of leachate secondary effluent using Poly‐aluminium(III)–magnesium(II) sulphate

Poly‐aluminium(III)–magnesium(II) sulphate (PMAS) was used to remove the colour from the secondary effluent of landfill leachate and the decolourization mechanism was researched. The results indicated that the decolourization efficiency using PMAS was better than the decolourization that occurred using other traditional coagulants, with a colour removal >90%. X‐ray diffraction and infrared spectrometry showed that PMAS was probably a type of macromolecular composite polymer of aluminium and magnesium that was based on –OH bonds. The coagulation mechanism of PMAS was primarily charge neutralization and coprecipitation netting, with charge neutralization being the dominant mechanism at low doses. In addition, the flocculation behaviour differed in response to various pH values of wastewater at high doses. Specifically, flocculation was primarily driven by charge neutralization at a low pH and coprecipitation netting at a high pH, while it occurred via a combination of these procedures under neutral conditions.     

成都地区居住建筑节能潜力与途径的分析探讨

深入分析各项节能技术是推动建筑节能的基础工作。本文首先采用DeST-h、WINDOWS5．2软件模拟实际项目全年采暖空调能耗,计算能量转换效率。而后模拟了,外窗型式对采暖空凋能耗的影响,比较采用屋顶隔热、热反射涂料与提高空凋EER等措施的节能效果。最后,探讨了该地区居住建筑节能的潜力和途径。     

中美FRP加固钢筋混凝土梁抗剪设计规范比较

纤维复合材(FRP)以其轻质、易安装、耐腐蚀等特点而倍受土木工程界的关注。根据美国ACI-440委员会编写的ACI 440.2R—08《FRP外黏加固混凝土结构设计与施工指南》,介绍了该指南中FRP加固混凝土梁斜截面抗剪承载力设计的适用范围和设计方法,并与我国GB 50367—2006《混凝土结构加固设计规范》中钢筋混凝土梁斜截面加固的计算方法进行对比分析,指出了两者在适用范围及设计方法上的异同点,为该方法的推广应用提供了参考。     

CRI处理氧化沟出水的效果及菌群分析

采用改进型人工快速渗滤系统(CRI)对氧化沟出水进行深度处理,对比分析添加/不添加玉米芯作为固体碳源的CRI系统对COD、氨氮、TN、TP的去除效果和机制,并对饱水段和非饱水段的微生物菌群进行Illumina高通量测序分析。结果表明,CRI对COD、NH4+-N、TN和TP的去除率分别达到60%～73. 3%、62. 5%～100%、57. 1%～89. 3%和85. 9%～99. 4%。CRI去除TP的主要途径是化学沉淀、渗滤介质吸附和微生物代谢等,其中海绵铁的高效化学除磷是主要作用。高通量测序结果表明,Proteobacteria、Bacteroidetes、Firmicutes和Acidobacteria是CRI内主要的门级菌群;但在属水平上,饱水层和非饱水层的厌氧菌、兼性菌、好氧菌、聚磷菌、硝化菌和反硝化菌等存在明显差异,这可能与溶解氧浓度和外加碳源有关。