变频规则波输入下直斜群桩动力响应对比试验研究

通过对2×2直斜群桩结构进行振动台模型相似比设计,围绕不同频率正弦波输入下的非液化砂土与饱和砂土中群桩-承台-上部结构体系开展横向动力响应特性试验研究。结果表明:①在输入相同频率正弦波情况下,无论是直桩群还是斜桩群,其位于饱和砂土中的动力响应放大倍数均大于相应非液化砂土工况下的放大系数,且直群桩的横向动力响应比斜群桩动力响应更显著;②随着输入波频率的增加,各试验工况的承台结构动力反应系数均有所增长,直桩群和斜桩群在饱和砂土工况中的加速度和位移的放大倍数增长较非液化砂土工况明显,直群桩比斜群桩增长显著。     

碳化硅陶瓷膜管对PM_(2.5)捕集性能的实验研究

PM2.5因其粒径小、吸附能力强、输送距离远、环境危害大,同时捕集困难而成为世界各国共同关注的大气环境问题。以涂氧化铝膜的碳化硅陶瓷膜管(孔隙率28.16%,平均孔径20μm,过滤面积0.28 m2)为过滤元件,搭建了PM2.5捕集的实验装置,对膜管的过滤时间、通量与阻力降的关系以及捕集效率与时间的关系和膜污染控制方面进行了研究。结果表明:随过滤时间增加,通量逐渐减小,阻力降逐渐增大,捕集效率逐渐增大,对PM2.5捕集效率高达99.9%;对膜污染控制参数优化后反吹压强选定为0.8 MPa,反吹间隔时间为10 min,反吹时间为14 s。     

柴油机排放颗粒物净化技术研究进展

柴油机被认为是城市大气微粒的主要污染源。柴油机颗粒物组成复杂并且颗粒粒径甚小,大都属于亚微米级粒子和纳米级粒子。因而柴油机颗粒物对人类健康和大气环境的影响受到世人的广泛关注。本文主要对柴油机排放颗粒物的生成机理、化学组成及危害、物理性质、检测方法和净化技术等方面进行综述与探讨。     

Relationships between distributions of longevous population and trace elements in the agricultural ecosystem of Rugao County,Jiangsu, China

Soil, plant, and water, as well as trace elements they contain, can influence human health through the food chain. A survey was conducted on distributions of trace elements in soils, plants, and drinking water in Rugao County, Jiangsu Province, China, an agricultural area with a high level of centenarians and nonagenarians. The ratio of people over 90 years old per 100,000 inhabitants (90-rate) based on village (about 4,000 residents in 4 km²) was correlated with trace elements in soil, drinking water, and rice by means of correlation analysis and/or principal component analysis. Although the average 90-rate in the whole area was as high as 277, the rates were not uniform across the entire region. The 90-rate in the area of loamy and strongly-developed Anthrosols and Cambosols was about 330, significantly higher than the 255 in the areas of sandy and strongly-developed Cambosols and of clayey and weakly-developed Cambosols. The concentrations of available Se, B, Ni, and Mo in soils of the area with the high 90-rate were markedly greater than those in the area with the low 90-rate. This was demonstrated by highly positive correlations between the 90-rate and available Se (r = 0.33), B (r = 0.21), Ni (r = 0.17) and Mo (r = 0.17) at the p < 0.01 level and high loadings of available Se (0.851), B (0.535), Ni (0.594) and Mo (0.394) in the longevous factor. Similar relationships between the available elements in soils and elements in water and rice were found. These results suggest that: (1) the available forms of elements in soil were more crucial to elemental bio-availability in the ecosystem and human health than total elements in soil; and (2) the element association above might have affected the 90-rate positively and could be an important environmental geochemical factor influencing the longevity of humans.     

鱼塘沉积物氯酚污染及其生态风险评价

采用固相微萃取(SPME)与气相色谱-质谱联用,分析了3种养殖模式鱼塘沉积物中氯酚类(CPs)化合物的污染特征.结果表明,一般四大家鱼养殖模式(A)沉积物中总CPs质量分数(干质量)为9.91 ng·g-1,猪.鱼综合养殖模式(B)与鸭-鱼综合养殖模式(C)沉积物总CPs质量分数分别为7.79 ng·g-1和4.84 ng·g-1.总CPs及15种CPs化合物在A、B模式和鸭-鱼综合养殖模式(C)沉积物中的分布特征相似,质量分数由高到低的顺序为A模式,B模式,C模式.沉积物中质量分数比较高的一氯酚、二氯酚、三氯酚和四氯酚分别是4-CP、2,4-DCP、2,4,6-TCP和2,3,4,6-TeCP.五氯酚(PCP)质量分数与4-CP、2,5+2,6+3,5-DCP、3,4-DCP、2,4,5-TCP、2,3,6-TCP、2,3,4-TCP、2,3,5,6-TeCP、2,3,4,6-TeCP、2,3,4,5-TeCP等氯酚化合物质量分数显著正相关,显示PCP与它们之间存在降解物与产物的关系.参照美国EPA相关标准,上述鱼塘沉积物中的PCP和Ky氯酚(2,3,4,6-TeCP、2,4,6-TCP和PCP)导致生态风险的可能性较低.     

Removal of cyanobacterial blooms in Taihu Lake using local soils. II. Effective removal of Microcystis aeruginosa using local soils and sediments modified by chitosan

After sepiolite was modified with Fe3+ to increase its surface charge, the initial algal removal rate increased significantly, but its Q8h was not improved substantially at clay loadings below 0.1 g/L. Modification on netting and bridging properties of clays by either chitosan or polyacrylamide (PAM) dramatically increased flocculation (Q8h) of MA cells in freshwaters. Algal removal efficiencies of different solids, including Type III clays, local soils and sediments, were all improved to a similar level of >90% at a total loading of 0.011 g/L (contained 0.001 g/L chitosan) after they were modified with chitosan, making the idea of clearing up algal blooms using local soils/sediments possible. The mechanism of netting and bridging was confirmed to be the most important factor in improving the removal efficiency of cells, whereas clays also played important roles in the sedimentation of the floc.     

Evaluating losses in ecosystem services in nature reserves in Sichuan,China

Nature reserves have developed rapidly over the decades in China and play a significant role in the function of ecosystem services. The function of ecosystem services in nature reserves, however, has tended to decline in recent years due to natural hazards and human activities. Based on land use, the variation of ecosystem services value (ESV) during 2000–2010 in national nature reserves in Sichuan was evaluated. We analyzed the comprehensive effects of natural disasters and human activities on the decline of ESVs. Total ESV in the national nature reserves in Sichuan was approximately 2741.35 million US$ in 2000, 2616.81 million US$ in 2005, and 2499.06 million US$ in 2010, representing a decrease of 242.29 million US$, or 8.84%, in the decade. Forestland, grassland, wetland, and water bodies played vital roles in the function of ecosystem services, with an aggregated ESV of 99% of the total. The largest proportion of the total ESV was the protection of biodiversity at 48.6%. ESV of all land use types and single ecosystem services continued to decline during 2000–2010. A mechanism of adaptable risk prevention should be established, and unreasonable human activities should be avoided to protect ecosystems and to improve the functions of ecosystem services.     

有机锡致海洋腹足类性畸变分子机制的研究进展

有机锡作为防污损生物附着添加剂曾被大量使用,在极低浓度下就能诱发腹足类发生性畸变现象,严重危害了海洋生态系统的平衡。虽然三丁基锡已被国际海事组织全球禁用,但目前报道的环境有机锡污染仍然非常严重,而且其致毒机制一直众说纷纭。首先,简述了腹足类性畸变及其在世界各个海域有机锡污染监测中的应用,重点综述了有机锡致海洋腹足类性畸变分子机制的3种假说:脊椎动物类型的类固醇激素假说、神经肽假说以及视黄酸X受体(retinoid X receptor,RXR)假说,另外,结合快速发展的分子生物学技术,探讨了研究腹足类性畸变分子机制的新思路和新方法。     

Experimental study on the feasibility of explosion suppression by vacuum chambers

In view of the invalidity of suppression and isolation apparatus for gas explosion, a closed vacuum chamber structure for explosion suppression with a fragile plane was designed on the base of the suction of vacuum. Using methane as combustible gas, a series of experiments on gas explosion were carried out to check the feasibility of the vacuum chamber suppressing explosion by changing methane concentration and geometric structure of the vacuum chamber. When the vacuum chamber was not connected to the tunnel, detonation would happen in the tunnel at methane volume fraction from 9.3% to 11.5%, with flame propagation velocity exceeding 2000 m/s, maximum peak value overpressure reaching 0.7 MPa, and specific impulse of shock wave running up to 20 kPa s. When the vacuum chamber with 5/34 of the tunnel volume was connected to the flank of the tunnel, gas explosion of the same concentration would greatly weaken with flame propagation velocity declining to about 200 m/s, the quenching distance decreasing to 3/4 of the tunnel length, maximum peak value overpressure running down to 0.1-0.15 MPa and specific impulse of shock wave below 0.9 kPa s. The closer the position accessed to the ignition end, the greater explosion intensity weakened. There was no significant difference between larger section and smaller vacuum chambers in degree of maximum peak value overpressure and specific impulse declining, except that quenching fire effect of the former was superior to the latter. The distance of fire quenching could be improved by increasing the number of the vacuum chambers.     

系统论在企业改造工程安全管理上的应用

运用系统论思想分析了企业大中修改造工程的特点,有针对性地提出了经实践检验行之有效、系统化的6项安全管理原则,具有较强的可操作性。