近15年来长江口控制站徐六泾悬沙变化特征研究

基于近15年的实测数据，分析给出了长江河口控制站徐六泾悬沙浓度和组成的变化特性。研究表明：徐六泾站多年平均表层（2003～2017年）、中层和底层（2010～2017年）含沙量分别为0.07、0.07和0.13 g/L；表层（2004～2017年）、中层和底层（2009～2017年）的中值粒径分别为7.3、9.4和11.0 μm。研究期间，年平均含沙量呈显著下降趋势，洪季较枯季降幅更明显。其中2015～2017年均洪枯季表层含沙量较2003～2005年均值分别降低了57%和20%；表层含沙量在2008年出现明显降低的拐点，2008年之后的洪枯季表层含沙量较之前分别降低56%和44%。悬沙粒度具有一定的波动变化，但没有显著趋势性变化特征，或与样本数量限制和流域内人类活动有关。     

废旧冰箱拆解聚氨酯泡沫塑料制备PU/PP复合材料

利用废旧冰箱拆解的聚氨酯泡沫塑料(PU)和聚丙烯(PP)、聚丙烯接枝马来酸酐(PP-g-MAH)为原料,采用物理化学回收技术制备PU/PP复合材料。用正交实验法分析PU填充量、PU粒径和PP-g-MAH 3个因素对PU/PP复合材料力学性能影响的显著性。结果表明,PU填充量对PU/PP复合材料拉伸性能有显著影响,对冲击性能和弯曲性能没有显著影响;在本文的实验范围内,PU粒径对PU/PP复合材料的力学性能影响不大;而PP-g-MAH投加量对PU/PP复合材料具有一定的影响。确定的优化工艺配方为:PU 40%;PU粒径选择2.00 mm;PP-g-MAH投加量10%。采用优化工艺制备的PU/PP复合材料的密度为1 042.88 kg/m3;冲击强度为2.9 kJ/m2;拉伸强度为10.30 MPa;拉伸模量为1 100 MPa;弯曲强度为18.5 MPa;弯曲模量为733 MPa。     

Preparation of biochar catalyst with saccharide and lignocellulose residues of corncob degradation for corncob hydrolysis into furfural

This paper presented a novel process for production of furfural by hydrothermal degradation of corncob over biochar catalyst, in which it was prepared with the recycling degradation solution and lignocellulosic solid residues. The biochar catalyst was papered by lignocellulose residues and concentrated saccharide solution, and then impregnated in 0.5 mol/L sulphuric acid at room temperature for 24 h assisted by the ultrasonic vibration. In the system of recycling, 8.8 % lignocellulose residues and 100 % concentrated saccharide solution from corncob hydrolysis have been recycled. Hydrolysis of corncob was carried out at 180 °C for duration of 170 min over the biochar catalyst. The experimental results have shown that the furfural yield of up to 37.75 % and overall corncob conversion rate of 62.00 % could be achieved under optimum operating conditions for the catalysts preparation and the corncob hydrolysis. It is believed that the acid density of 4.27 mmol/g of biochar catalyst makes the SO₃H groups cleave β-1,4 glycosidic linkages effectively and hydrolyze the cellulose and hemicellulose to water-soluble sugars, as well as to facilitate dehydration of xylose to give the product of furfural.     

1900～2018年全球自然灾害时空演变特征与相关性研究

全球紧急灾难数据库EM-DAT(Emergency Events Database,简称EM-DAT)中1900～ 2018年的自然灾害数据,综合趋势检验及突变点检测方法、标准差椭圆空间统计方法,探究灾害的时空分布、演变趋势及不同灾害之间的相关性.结果 表明:(1)洪水、干旱和风暴的危害性较大.其中,洪水发生次数最多,干旱造成的死亡人数最多,风暴造成的经济损失最为惨重;(2)从时间上来看,灾害发生次数先增加后稍有减少,总体呈上升趋势;因灾死亡人数则自1932年后大幅度减少,呈下降趋势;灾害经济损失持续增加,呈上升趋势;(3)从空间上来看,灾害发生次数分布格局呈南北方向扩张、东西方向收缩趋势,整体往东南方向移动;灾害死亡人数空间分布先呈现西北-东南分布格局,后转变成西南-东北格局,且这种格局不断弱化,直到最后重新呈现西北-东南分布格局;灾害经济损失重心东西方向移动距离大于南北方向,经济损失主方向总体向西北方向转移;(4)洪水、风暴、地震、流行病、滑坡5种灾害与所有灾害均呈显著正相关,相关性系数都达到0.57以上,相互作用较强,其中,地震与风暴两种灾害间的相关性系数最高(为0.906).     

近岸海域水质目标考核评价方法研究

为满足《水污染防治行动计划》近岸海域水质考核要求,根据目前近岸海域环境监测工作的实际情况,在考核范围、评价方法、目标分解、计分方法等方面进行了比较,在保证公平、公正的前提下,以一致性、可比性和适应性为原则,提出的考核评价方法以单因子评价法和点位评价法为基础,在未达标情况下,按照水质目标完成比例计分;达标情况下,在达标分值基础上按水质的保持和改善给予不同程度的加分,通过实例研究分析能够适应近岸海域水质状况变化的考核工作要求。     

国产多核处理器芯片TDBI技术研究

随着集成电路的功能越来越复杂,超大规模集成电路的动态老炼越来越成为一项困难的工作。传统针对超大规模集成电路的老炼多采用静态老炼方法,这种方法不能使电路内部的功能节点动作起来,无法保证老炼效果,因此能够实现电路内部所有功能模块全动态激励的TDBI技术越来越受到人们的关注。本文以国产多核处理器芯片为测试对象,为研究多核处理器芯片的TDBI方法进行了芯片老炼测试软硬件系统开发,解决了多核处理器老炼中大功率电源供电、图形存储空间不足等关键技术。     

Influence of filtration velocity on DON variation in BAF for micropolluted surface water treatment

Biological aerated filters (BAFs) are widely used for the treatment of micropolluted surface water. However, the biological process produces dissolved organic nitrogen (DON), which, as precursors of nitrogenous disinfection by-products, pose potential threats to drinking water safety. Therefore, to control DON in BAF effluent, it is necessary to study the influence of BAF operation parameters on DON production. In this study, the influence of filtration velocity in a BAF on DON production was investigated. Under different filtration velocity (0.5, 2, and 4 m/h) conditions, profiles of DON concentrations along the media layer were measured. The profile at a filtration velocity of 0.5 m/h showed a decreasing trend, and the ones under filtration velocities of 2 and 4 m/h fluctuated in a small range (from 0.1 to 0.4 mg/L). Moreover, the relatively high filtration velocities of 2 and 4 m/h resulted in a lower level of DON concentration. Additionally, 3D excitation-emission matrix fluorescence spectroscopy was used to characterize DON. It is found that the patterns of DON at a relatively high filtration velocity condition (4 m/h) were obviously different from the ones under low filtration velocity conditions (0.5 and 2 m/h).     

Adsorptive conversion of nitrogen dioxide from etching vent gases over activated carbon

Some metal etching operations emit limited flow rates of waste gases with reddish-brown NO₂ fume, which may cause visual and acidic-odor complaints, as well as negative health effects. In this study, tests were performed by passing caustic-treated waste gases vented from Al-etching operations through columns packed either with virgin or regenerated granular activated carbon (GAC) to test their adsorptive conversion performance of NO₂ in the gases. The gases contained 5–55 ppm NO₂ and acetic and nitric acids of below 3 ppm. Exhausted carbon was regenerated by scrubbing it with caustic solution and water, and dried for further adsorption tests. Results indicate that with an (empty bed residence time (EBRT) of 0.15 sec for the gas through the GAC-packed space, around 60% of the influent NO₂ of 54 ppm could be removed, and 47% of the removed NO₂ was converted by and desorbed from the carbon as NO. GAC used in the present study could be regenerated at least twice to restore its capacity for NO₂ adsorption. Within EBRTs of 0.076–0.18 sec, the adsorptive conversion capacity was linearly varied with EBRT. In practice, with an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO₂ (kg GAC)^?1 with an influent NO₂ of 40 ppm can be used as a basis for system design.

Implications: Some metal etching operations emit waste gases with reddish-brown (yellow when diluted) NO₂ fume which may cause visual and acidic-odor complaints, as well as negative health effects. This study provides a simple process for the adsorptive conversion of NO₂ in caustic-treated waste gases vented from metal-etching operations through a GAC column. With an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO₂ (kg GAC)^?1 with an influent NO₂ of 40 ppm can be used as a basis for system design. Saturated GAC can be regenerated at least twice by simply scrubbing it with aqueous caustic solution.     

Diurnal concentrations variations,size distributions for ambient air particles and metallic pollutants (Cr,Mn, Ni,Cd, Pb) during summer season at a traffic area

This study characterized and discussed particulate ambient air particulate concentrations and seasonal variations for PM₁₈, PM₁₀, PM_2.5, and PM₁ during June 2013–July 2013 at this traffic sampling site. In addition, this study also characterized the ambient air particulates size distributions by using MOUDI-100S4 sampler to collect 1-day the ambient suspended particles (PM₁₈, PM₁₀, PM_2.5, and PM₁) at this sampling site. In addition, the study also showed that the main pollutants contributions were from traffic and residual areas. As for the pollutants seasonal concentrations variations, the results indicated that the average particle concentrations orders were all displayed as daytime?>?nighttime for PM₁₈, PM₁₀, PM_2.5 and PM₁ at this characteristic sampling site. The results further indicated that the mean highest of metal concentrations in this study indicated that the average metal concentration were all displayed as Mn?>?Cr?>?Ni?>?Pb?>?Cd for PM₁₈, PM₁₀, PM_2.5 and PM₁ on daytime and nighttime at this characteristic sampling site.