CuO/AC@SiO_2的制备及对H_2S的深度脱除

采用模板法在CuO外包裹一层具有介孔结构的SiO_2,制备了CuO/AC@SiO_2。采用X射线衍射仪对CuO/AC@SiO_2的结构和催化活性位点进行了表征。通过固定床气固吸附实验,研究了CuO/AC@SiO_2对H_2S的吸附脱除性能。表征结果显示,CuO是催化氧化H_2S的活性中心,被氧化成Cu2O后吸附脱除H_2S的性能下降。实验结果表明:CuO/AC吸附H_2S时的有效穿透时间为117 min,CuO/AC@SiO_2的有效穿透时间提高到141 min,CuO/AC@SiO_2对H_2S的吸附性能明显提高;以Cu(NO_3)_2为前驱体的CuO/AC@SiO_2对H_2S的吸附量高于以Cu(AC)_2为前驱体;在Cu(NO_3)_2为前驱体、m(正硅酸乙酯)∶m(CuO/AC)=0.7、吸附温度为90℃的最佳条件下,CuO/AC@SiO_2对H_2S的吸附量达17.40 mg/g。     

Beta-normal distribution in dose–response modeling and risk assessment for quantitative responses

To establish allowable daily intakes for humans from animal bioassay experiments, benchmark doses corresponding to low levels of risk have been proposed to replace the no-observed-adverse-effect level for non-cancer endpoints. When the experimental outcomes are quantal, each animal can be classified with or without the disease. The proportion of affected animals is observed as a function of dose and calculation of the benchmark dose is relatively simple. For quantitative responses, on the other hand, one method is to convert the continuous data to quantal data and proceed with benchmark dose estimation. Another method which has found more popularity (Crump, Risk Anal 15:79–89; 1995) is to fit an appropriate dose–response model to the continuous data, and directly estimate the risk and benchmark doses. The normal distribution has often been used in the past as a dose–response model. However, for non-symmetric data, the normal distribution can lead to erroneous results. Here, we propose the use of the class of beta-normal distribution and demonstrate its application in risk assessment for quantitative responses. The most important feature of this class of distributions is its generality, encompassing a wide range of distributional shapes including the normal distribution as a special case. The properties of the model are briefly discussed and risk estimates are derived based on the asymptotic properties of the maximum likelihood estimates. An example is used for illustration.

剪切速率及法向应力对煤散体抗剪强度影响研究

在煤层巷道垮落后需安全快速地开挖出1条应急救援巷道,为了了解开挖速率和法向压力对救援巷道稳定性的影响,通过将垮落的破碎煤视为均质散粒体的方式,采用相似模拟实验的手段,分析了剪切速率和法向压力对煤散体抗剪强度的影响。研究结果表明:煤散体的抗剪强度与其对应的法向应力存在线性关系,该关系近似符合莫尔库仑强度准则,但剪切强度增长率随法向压力增大而先增大后减小;在相同法向应力作用下,剪切速率对黏聚力的影响明显大于对内摩擦角的影响。     

LPG充装站紧急切断阀失效模式分析

紧急切断阀作为LPG充装站的重要安全附件之一,当遇到突发情况时,可远程控制紧急切断阀迅速关闭,避免事故的进一步蔓延。若LPG充装站紧急切断阀安装位置不合理,或缺乏定期检验检查与维护保养,均可能导致紧急切断失效。通过对LPG充装站紧急切断阀的工作原理及安装位置,常见失效模式分析及预防,定期检验检查及维护保养注意事项进行详细研究,为LPG充装站对紧急切断阀进行年度检查及维护保养和相关检验单位进行定期检验提供参考。     

晚中新世以来帕米尔高原生长过程及其与塔里木盆地气候变化可能的联系

帕米尔高原是我国极端干旱区——塔里木盆地的西部边界,也是青藏高原西部构造结所处的位置,所以,它的构造演化过程对于研究青藏高原生长过程及塔里木盆地的干旱化历史具有重要的意义。本文通过帕米尔高原东北部正断裂活动的空间展布、活动性质及运动时代的分析,结合最近构造观测结果,提出帕米尔高原在晚中新世已经隆升到了能够影响西风气流通过的高度。尽管高原在晚中新世已经存在东西向的拉张应力,木吉-塔什库尔干谷地可能最终形成于早-中更新世。这一事件奠定了作为喜马拉雅山到南天山之间过渡的帕米尔高原的现今地貌形态及塔里木盆地的气候特征背景。本文结合西昆仑北部及南天山的古地理演化及构造运动证据分析,提出帕米尔高原晚中新世以来的构造地貌演化可能是塔里木盆地晚中新世干旱化加剧的主要原因,中更新世气候代用指标解释复杂性可能也与此密切相关,全球变冷和特提斯海西退可能对晚中新世以来的气候变化也有一定的贡献。     

环氧树脂生产废水常温常压下催化氧化处理方法研究

采用常温常压催化氧化工艺处理环氧树脂生产废水,通过实验发现,采用南京博环环保有限公司开发的负载型催化剂可以获得较好的效果.在常温常压,进水pH为3.5～5.5,氧化时间为0.5h的条件下,COD的去除率可达到85％.     

垂直发射装置排气道极限承压性能分析

目的研究导弹在意外点火时排气道的力学性能及导弹发射的安全性,对排气道的极限承压性能进行研究。方法建立排气道的极限承压的仿真模型,通过水压试验及发射试验,获取排气道不同种试验方式下的极限承压数据。结果排气道在导弹正常发射时承压设计值为0.3 MPa。极限承压仿真试验过程中,排气道在受到0.5 MPa压强时,所受应力超过材料最大抗拉极限。水压试验过程中,排气道受0.58 MPa压强时,其结构发生破坏。意外点火试验过程中,排气道所受最大压强值为0.24 MPa。结论排气道的极限承压能力可以满足正常发射及意外点火的发射要求,排气道的设计裕量充足。     

常压法测定煤层瓦斯含量的误差分析

为了校正脱气法和常压法测量瓦斯含量的误差。通过理论分析、模型计算和实验对比的方法,研究煤样气体自然成分含二元和三元混合气体时的误差来源。查明气体成分为N2和CH4时,该误差可通过系数法进行修正;气体成分含CO2,CH4和N2 3种气体时,误差可通过扩展的langmuir模型修正。水分对测定误差的影响为:烟煤中含氧官能团与水优先结合后,影响煤孔网吸附点的可达性,导致水分与测定误差线性相关;无烟煤表面积大且表面官能团减少,水分的优先吸附使煤表面性质更均匀,水分与气体分子竞争煤表面的相同吸附点,水分与测定误差负相关。该结论对煤层瓦斯含量测定方法的选择和修正有重要意义。     

Indoor radon levels in Greek schools

Radon and gamma dose rate measurements were performed in 512 schools in 8 of the 13 regions of Greece. The distribution of radon concentration was well described by a lognormal distribution. Most (86%) of the radon concentrations were between 60 and 250 Bq m⁻³ with a most probable value of 135 Bq m⁻³. The arithmetic and geometric means of the radon concentration are 149 Bq m⁻³ and 126 Bq m⁻³ respectively. The maximum measured radon gas concentration was 958 Bq m⁻³. As expected, no correlation between radon gas concentration and indoor gamma dose rate was observed. However, if only mean values for each region are considered, a linear correlation between radon gas concentration and gamma dose rate is apparent. Despite the fact that the results of radon concentration in schools cannot be applied directly for the estimation of radon concentration in homes, the results of the present survey indicate that it is desirable to perform an extended survey of indoor radon in homes for at least one region in Northern Greece.