高层建筑管道井内烟气运动大涡模拟

采用火灾过程的场模拟理论,以大涡模拟为基础,分析了火灾烟气流动过程的动力学特征;为了验证大涡模拟数值方法的准确性,针对Mercier和Jaluria竖井内的实验工况进行了模拟研究,其模拟结果与试验结果吻合较好,表明大涡模拟可以较好地预测竖井内烟气流动情况;通过设定不同的火灾场景,对不同火源功率和不同几何尺寸条件下管道井内烟气的流动过程进行了数值模拟,其结果给出了不同的几何尺寸和火源功率对管道井内所形成“烟囱效应”的影响情况。笔者的模拟和研究表明:大涡模拟可较准确地预测高层建筑管道井内烟气的流动状态,对高层建筑的防火设计具有指导性作用。     

甘氨酸厂工业废水蒸发冷凝液的治理

采用Fenton氧化法对含有高浓度COD的冷凝水进行了试验研究.结果表明,在[H₂O₂]/[Fe²⁺]=3.6:1、温度为30℃、 3.0的条件下,COD pH的去除率为 65%;在加入紫外光照射的情况下,冷凝液的 COD 去除率可提高到 77%.     

基于监测数据的边坡参数统计特征及可靠度更新∗

掌握详细的边坡岩土体参数信息是进行边坡加固与风险评估的重要前提。目前大多采用马尔可夫链蒙特卡洛模拟方法基于现场或室内试验数据进行不确定性参数统计信息及边坡可靠度更新。然而,该方法存在计算量大、计算结果不易收敛和难以解决高维边坡不确定性参数统计特征及可靠度更新等问题。本文基于粒子群优化反向传播神经网络算法建立边坡位移代理模型优化计算过程,提出了改进的基于子集模拟的贝叶斯更新方法,进而基于边坡变形监测数据进行参数统计特征及可靠度更新。最后,将提出方法应用到长春西客站深基坑边坡工程。 结果表明：提出方法能够融合有限的场地信息有效地更新边坡岩土体参数统计特征,推断其后验概率密度函数,进而更新边坡失效概率。利用更新的土体参数计算的边坡位移与实测数据吻合,验证了提出方法的适用性和有效性。另外融合监测数据进行贝叶斯更新之后,虽然土体参数的不确定性明显降低,但是边坡失效概率受外界气温、 监测点位置及数据量值的影响会增大。     

沸石负载Fe_3O_4光催化氧化去除水中苯酚

为了对水中苯酚的去除进行研究,通过离子交换法及液相沉积法在天然沸石上负载Fe3O4制备出一种具有较高反应活性的复合催化剂,采用X-射线衍射仪(XRD)、扫描电镜(SEM)等仪器对其结构和形貌进行表征,并利用复合催化剂进行非均相UV/Fenton反应处理模拟苯酚废水,考察不同因素对苯酚降解效果的影响。实验结果表明,在催化剂投加量为0.4 g/L,H2O2投加量为二分之一理论投加量,pH为3~10且室温的条件下,处理100 mg/L的模拟苯酚废水,60 min之内苯酚去除率可达90%以上。通过对催化剂的稳定性研究,发现经5次循环使用后,苯酚去除率均可保持在90%以上,具有良好的循环使用性能。     

Contributions of global and regional sources to mercury deposition in New York State

A modeling system that includes a global chemical transport model (CTM) and a nested continental CTM (TEAM) was used to simulate the atmospheric transport, transformations and deposition of mercury (Hg). Three scenarios were used: (1) a nominal scenario, (2) a scenario conducive to local deposition and (3) a scenario conducive to long-range transport. Deposition fluxes of Hg were analyzed at three receptor locations in New York State. For the nominal scenario, the anthropogenic emission sources (including re-emission of deposited Hg) in New York State, the rest of the contiguous United States, Asia, Europe, and Canada contributed 11-1, 25-9, 13-19, 5-7, and 2-5%, respectively to total Hg deposition at these three receptors. Natural sources contributed 16-4%. The results from the local deposition and long-range transport scenarios varied only slightly from these results. However, there are still uncertainties in our understanding of the atmospheric chemistry of Hg that are likely to affect these estimates of local, regional and global contributions. Comparison of model simulation results with data from the Mercury Deposition Network suggests that local and regional contributions may currently be overestimated.     

The effectiveness of lane departure warning systems—A reduction in real-world passenger car injury crashes

Objective: The objective of this study was to estimate the safety benefits of in vehicle lane departure warning (LDW) and lane keeping aid (LKA) systems in reducing relevant real-world passenger car injury crashes.

Methods: The study used an induced exposure method, where LDW/LKA-sensitive and nonsensitive crashes were compared for Volvo passenger cars equipped with and without LDW/LKA systems. These crashes were matched by car make, model, model year, and technical equipment; that is, low-speed autonomous emergency braking (AEB) called City Safety (CS). The data were extracted from the Swedish Traffic Accident Data Acquisition database (STRADA) and consisted of 1,853 driver injury crashes that involved 146 LDW-equipped cars, 11 LKA-equipped cars, and 1,696 cars without LDW/LKA systems.

Results: The analysis showed a positive effect of the LDW/LKA systems in reducing lane departure crashes. The LDW/LKA systems were estimated to reduce head-on and single-vehicle injury crashes on Swedish roads with speed limits between 70 and 120 km/h and with dry or wet road surfaces (i.e., not covered by ice or snow) by 53% with a lower limit of 11% (95% confidence interval [CI]). This reduction corresponded to a reduction of 30% with a lower limit of 6% (95% CI) for all head-on and single-vehicle driver injury crashes (including all speed limits and all road surface conditions).

Conclusions: LDW/LKA systems were estimated to lower the driver injury risk in crash types that the systems are designed to prevent; that is, head-on and single-vehicle crashes. Though these are important findings, they were based on a small data set. Therefore, further research is desirable to evaluate the effectiveness of LDW/LKA systems under real-world conditions and to differentiate the effectiveness between technical solutions (i.e., LDW and LKA) proposed by different manufacturers.     

Investigation of physico-chemical properties and microbial community during poultry manure co-composting process

Co-composting of poultry manure and rubber wood sawdust was performed with the ratio of 2:1 (V/V) for a period of 60 days. An investigation was carried out to study the extracellular enzymatic activities and structural degradation utilizing Fourier transform infrared spectroscopy (FT-IR), thermogravimetry and differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM). The microbial succession was also determined by using denaturing gel gradient electrophoresis (DGGE). The compost was able to reach its highest temperature of 71°C at day 3 and stabilized between 30 and 40°C for 8 weeks. CMCase, FPase and β-glucosidase acted synergistically in order to degrade the cellulosic substrate. The xylanase activities increased gradually during the composting and reached the peak value of 11.637 U/g on day 35, followed by a sharp decline. Both LiP and MnP activities reached their peak values on day 35 with 0.431 and 0.132 U/g respectively. The FT-IR spectra revealed an increase in aromaticity and a decrease in aliphatic compounds such as carbohydrates as decomposition proceeded. TGA/DTG data exhibited significant changes in weight loss in compost samples, indicating degradation of organic matter. SEM micrographs showed higher amounts of parenchyma exposed on the surface of rubber wood sawdust at day 60, showing significant degradation. DGGE and 16S rDNA analyses showed that Burkholderia sp., Pandoraea sp., and Pseudomonas sp. were present throughout the composting process. Ornithinibacillus sp. and Castellaniella ginsengisoli were only found in the initial stage of the composting, while different strains of Burkholderia sp. also occurred in the later stage of composting.     

葛根去除水溶液中亚甲基蓝的生物吸附机理和特性

对农副产品葛根吸附水溶液中亚甲基蓝的特性和机理进行了一系列的研究。考察了不同条件对吸附效果的影响;采用2种等温线模型和3种动力学模型对吸附机理和动力学特性进行了模拟分析,并计算了相关的热力学函数。结果发现,溶液pH值等实验条件对吸附效果有较大的影响;Langmuir方程能很好地描述其吸附等温线,吸附是一个符合二级动力学过程的物理吸附;热力学函数计算结果显示,此吸附是一个自发的放热过程。在3种不同温度下,由Langmuir方程计算的最大吸附量为98.23、91.04和87.28 mg/g,表明葛根是一种良好的,具有一定发展潜力的染料吸附剂。