西安地铁穿越地裂缝带支护结构设计研究

西安地裂缝是一种地区性的地质灾害,地裂缝的存在给西安地铁的设计和施工等带来一系列的难题和挑战.本文针对西安地铁1号线与F6地裂缝的交叉进行了支护结构设计的探讨分析,调查了F6地裂缝的活动规律和特点.在此基础上,建立了三维有限元计算模型,确定模型的加载方式,分析研究了地铁隧道在施工、支护阶段以及设计年限内最终沉降的结构受力与变形,从而确定了结构设计的方式以及布置形式.同时探讨了支护结构构造,给出了变形缝处结构协调地裂缝活动措施和方法,以期本研究对西安地裂缝带的地铁建设有一定参考.     

Influence of air flow rate on emission of DEHP from vinyl flooring in the emission cell FLEC: Measurements and CFD simulation

The emission of di-(2-ethylhexyl)phthalate (DEHP) from one type of vinyl flooring with ～15% (w/w) DEHP as plasticizer was measured at 22 °C in five FLECs + one blank FLEC (Field and Laboratory Emission Cell). Initially, the flow through all FLECs was 450 ml min^?1. After 689 days the flows were changed to 1000 ml min^?1, 1600 ml min^?1, 2300 ml min^?1, and 3000 ml min^?1, respectively, in four FLECs, and kept at 450 ml min^?1 in one FLEC. Air samples were collected from the effluent air at regular intervals. After 1190 days the experiments were terminated and the interior surfaces of all six FLECs were rinsed with methanol to estimate the internal surface concentrations of DEHP. The DEHP air concentration and specific emission rate (SER) at steady state was estimated for the five different flow rates. The steady-state concentrations decreased slightly with increasing air flow with only the two highest flow rates resulting in significantly lower concentrations. In contrast, the SERs increased significantly. Despite large variation, the internal surface concentrations appeared to decrease slightly with increasing FLEC flow. Computational fluid dynamic (CFD) simulations suggest that the interior gas and surface concentrations were roughly uniform for the low flow case (450 ml min^?1), under which, the partitioning between the FLEC internal surface and chamber air was examined. Although paired t-tests showed no difference between CFD and experimental results for DEHP air concentrations and SERs at steady-state conditions, CFD indicated that the experimental DEHP surface concentrations in the FLECs were underestimated. In conclusion, the experiments showed that the emission of DEHP from vinyl flooring is subject to “external” control and that the SER is strongly and positively dependent on the air exchange rate. However, the increased SER almost compensates for the decrease in gas-phase concentration caused by the increased air exchange.     

TiO2诱导下左旋氧氟沙星的可见光降解及其机制

左旋氧氟沙星是一种新型污染物.单一的左旋氧氟沙星(LFV)和Ti O2无可见光响应,但二者共存下左旋氧氟沙星能发生显著的可见光降解.为此研究Ti O2用量、溶液p H以及左旋氧氟沙星浓度对Ti O2/Vis(可见光)降解左旋氧氟沙星的影响及机制.结果表明,左旋氧氟沙星能吸附在Ti O2表面,吸附服从准二级吸附动力学和Langmuir吸附等温线.吸附左旋氧氟沙星的Ti O2漫反射UV-Vis光谱进一步表明二者形成表面复合物.左旋氧氟沙星的Ti O2/Vis降解动力学符合LangmuirHinshelwood方程.合适的Ti O2浓度和中性p H有利于光解过程的进行.自由抑制实验、N2保护下左旋氧氟沙星的Ti O2/Vis降解实验揭示·O-2是该过程中的主要活性物种.同时,无氧左旋氧氟沙星-Ti O2悬浮液光照不同时间的UV-Vis光谱证明体系中存在电子向Ti O2导带的注入.依据实验结果提出吸附在Ti O2表面的左旋氧氟沙星与Ti O2形成表面复合物,在可见光照下发生电子迁移,从而引发左旋氧氟沙星降解.本研究表明利用污染与Ti O2形成表面复合物诱导其可见光降解可用来去除水中某些有机污染物.     

某产品钛合金性能及台阶轴磨削

TC4因具有良好的力学性能和较好的工艺性能而成为钛合金结构件中使用最多的材料,但其磨削性极差,特别是台阶轴的磨削更为困难。在吸取总结各种磨削经验的基础上对钛合金台阶轴的磨削做了一些探索和实践。     

Study of a proposed tunnel evacuation passageway formed by opposite-double air curtain ventilation

Subway tunnel fires often result in catastrophes and heavy casualties. To help people evacuate from a tunnel fire, an opposite-double air curtain ventilation assisted tunnel evacuation system (OTES) is introduced. It can be used to create a safe evacuation passageway that is free of smoke through out the length of the tunnel. The performance of the OTES is compared with that of the traditional ventilation systems: longitudinal ventilation and natural ventilation. The effect of the heat release rate, fire source location, and fire detection time are also discussed.This study also shows that compared with natural ventilation and longitudinal ventilation, the carbon monoxide, CO, concentration with OTES is significantly lower. Given the same HRR, the CO concentration values with OTES are only 0.58–2.41% of natural ventilation or 0.52–3.12% of longitudinal ventilation at the back end of the tunnel. An obviously clear evacuation passageway is created by OTES. The effects of changes in fire source location and fire detection time on tunnel ventilation are tested. Also the effect of these changes on the formation of an evacuation passageway by OTES is reported.     

鼠李糖脂对铜绿假单胞菌NY3表面特性及其烃降解效率的影响

研究了鼠李糖脂对NY3菌表面特性及其降解烃类物质的影响作用.结果表明,与未加鼠李糖脂相比,原油含量为1000 mg·L-1,鼠李糖脂100 mg·L-1时,生长24和48 h,NY3菌细胞净生长量分别提高8.60和6.68倍,且产酸明显,原油中正二十六烷至正三十三烷降解效率可提高约60%.分别以LB培养基和十六烷为唯一碳源的无机盐培养基生长的NY3菌体(OD400nm=1.68±0.08),与100 mg·L-1的鼠李糖脂作用1.5h,菌体表面疏水性分别增加32%、6%;且以LB培养基生长的NY3菌细胞,在鼠李糖脂和十六烷存在下作用90 min,菌细胞所积聚的正十六烷量比未加鼠李糖脂时增加了1.10 nmol·mg-1干菌,说明鼠李糖脂能加快疏水性有机物的传质速度.红外光谱分析结果表明,与未加鼠李糖脂相比,鼠李糖脂使菌体细胞中疏水性脂肪链的相对含量明显增加.因此,鼠李糖脂能增加菌体的表面疏水性,加快烃类的传质速率,从而促进NY3菌对烃的降解.     

中空夹层钢管混凝土柱受力性能研究

为研究不同空心率对中空夹层钢管混凝土柱的受力性能的影响,对3个不同空心率的中空夹层钢管混凝土柱试件和1个普通钢管混凝土柱试件进行了非线性有限元分析.结果表明:与普通钢管混凝土柱相比,中空夹层钢管混凝土柱承载力和刚度有了明显的提高,塑性和延性性能也相应提高.中空夹层钢管混凝土柱受力性能更加合理,它充分利用了钢材和混凝土各自受力性能的优势,大幅提高了建筑结构的安全性能,是一种发展前景非常广阔的结构形式.     

ISO/FDIS9223:2011E中剂量响应函数应用浅析

采用剂量响应函数法、关键因素法、标准金属法评估了我国9个大气腐蚀试验站的大气腐蚀特性,探讨了ISO/FDIS 9223：2011E中剂量响应函数的适用范围、评估误差、温湿度对SO2和Cl-腐蚀性的影响等。分析表明,剂量响应函数法适用于评估有SO2或Cl-污染的大气环境腐蚀性,评估效果与ISO 9223—1992中的关键因素法相当,响应函数式中温度、湿度对污染物的腐蚀作用影响还有待进一步验证。     

旅客列车集便器废水中抗生素的光芬顿催化降解分析

旅客列车集便器废水中含有一定量生物难降解的磺胺甲恶唑（SMX）抗生素,使用光芬顿法对集便器废水中残留的抗生素进行催化降解,并对其机理进行分析。制备反应催化剂氧基氯化铁（FeOCl）,并利用XRD、SEM、XPS等表征手段证明制备的FeOCl具有典型的长方体形状、层片状结构;实验模拟并对比7种不同催化条件下旅客列车集便器废水中SMX的降解效果,得出最优降解条件为H₂O₂浓度为8 mmol/L,FeOCl粉末投加量为0.2 g/L,SMX初始浓度为0.1 mmol/L;在最优条件下定量分析了体系中H₂O₂和NH₄+-N浓度的变化,及溶液中5种常见阴离子对SMX降解过程的抑制作用,为旅客列车集便器废水中抗生素降解的中试实验提供一定的理论和数据基础。     

园林生物质中离子液体-复合菌剂共降解体系的筛选与构建

园林生物质的绿色高效降解是实现生态系统物质循环的重要环节,离子液体-生物酶作为环境友好型降解体系备受关注.通过合成1-丁基-3-甲基咪唑（[Bmim]）和1-乙基-3-甲基咪唑（[Emim]）型离子液体衍生物,比较了温和条件下各离子液体对园林生物质的溶解再生性.结合复合微生物菌剂开展酶解试验,通过考察酶解率、纤维素酶活力、降解失重率和木质素含量变化等,筛选并构建最优降解体系组合.结果表明,两种离子液体的盐取代物对园林生物质有着较好的溶解再生性,当质量分数为70%~80%时,[Emim]型离子液体-复合菌剂体系的酶解率和酶活力最高.在降解末期,[Emim]Ac_75%和[Emim]FeCl_4·75%体系的降解失重率分别为46.9%和52.6%,均为阳性对照组的1.6倍,同时木质素含量分别减少41.7%和47.2%.[Emim]FeCl_4·75%-复合菌剂体系对园林生物质有着更为显著的降解效应.