Determination of persistent organic pollutants by gas chromatography/laser multiphoton ionization/time-of-flight mass spectrometry

An authentic mixture of polychlorinated biphenyls was measured using a short wide-bore capillary column for the group separation of major components present in an actual sample of Kanechlor. The limits of detection were improved by ca. 2 fold in comparison with those obtained using a conventional capillary column, since the retention time was reduced and the amount of analytes introduced into the mass spectrometer per unit time could be increased. On the other hand, surface-water and sediment samples containing polycyclic aromatic hydrocarbons (PAHs) were collected from the river located in the vicinity of a waste water treatment plant. Even acenaphthylene, a minor component of the mixture could be measured for the sediment sample, and the concentrations were determined for several heavy PAHs. As demonstrated, a technique involving laser multiphoton ionization/time-of-flight mass spectrometry was useful as a sensitive and selective analytical tool for the trace analysis of persistent organic pollutants in an environmental sample.     

基于3D激光扫描技术的绕腰法采空区资源回收方法研究

针对大多数矿山采空区残留资源回收探测中存在人员、设备进入难,精度低、危险高等问题,我们通过采用三维激光扫描技术恰恰克服了以上困难。应用三维激光自动扫描新技术对采空区进行精密探测,能够安全准确地获取采空区的三维形态和矿石空间分布位置,再通过三维建模软件 Surpac 建立三维可视化实体模型,为回收残留矿石资源提供重要依据;最后通过应用绕腰法综合回收残留矿石,不仅能够减少采准工程量,并把采准与采矿工作很好地结合起来,而且达到了能够高效安全地回采采空区残留矿石目的。工程实例的成功应用,表明此方法在给矿山和国家带来良好的经济社会效益的同时,能够在同类矿山中推广应用。     

Effect of placement angles on wireless electrocoagulation for bipolar aluminum electrodes

A new electrocoagulation process based on bipolar aluminum electrode is proposed. The placement angles of bipolar electrode are key parameter. The numerical simulations support the experimental results. We in our previous study reported the wireless electrocoagulation (WEC) based on bipolar electrochemistry for water purification. One of the most important advantages of WEC is the omission of ohmic connection between bipolar electrode (BPE) and power supply, and thus the electrochemical reactions on BPE are driven by electric field in solution induced by driving electrodes. In this study, the impact of placement angle of bipolar aluminum electrode on WEC was investigated to provide a detailed analysis on the correlations between the bipolar electrode placement angle and bipolar electrocoagulation reactions. The results showed that the WEC cell with a horizontal BPE placed at 0° produced the maximum dissolved aluminum coagulant, accounting for 71.6 % higher than that with a vertical one placed at 90°. Moreover, the finite element simulations of current and potential distribution were carried out along the surface of BPE at different placement angles, revealing the mechanism of different BPE placement angles on aluminum dissolution rates in WEC system.     

考虑峰后软化的圆形巷道稳定性分析及工程应用

为获得更准确的巷道围岩应力分布和变形特征,基于统一强度理论,考虑围岩塑性软化和中间主应力的影响,引入塑性软化参数,推导出巷道围岩弹塑性区应力、塑性区范围和位移的表达式。通过算例分析,得到塑性软化系数和中间主应力等相关参数对巷道围岩应力分布、塑性区半径和位移的影响规律。研究结果表明:随内摩擦角软化系数和黏聚力软化系数的增大,围岩塑性区半径和位移呈现先急剧后缓慢的减小趋势;中间主应力系数对巷道围岩弹塑性应力有着显著影响,中间主应力系数越大,围岩塑性区半径和位移越小。     

高速气固两相流作用下的煤化工管材冲蚀磨损行为研究

为解决煤化工业中节流阀突扩口高速气固两相流对管壁材质的冲蚀磨损问题,利用基于激波管原理驱动的气固两相流冲蚀实验装置,试验研究冲击角度、温度对煤化工管材(10#、AISI304)的冲蚀磨损规律。研究结果表明:10#、AISI304管材的冲蚀率将随着冲击角度的增加而先增大后减小;室温下,10#、AISI 304钢的最大冲蚀率均出现在15°~30°区间;随着温度的升高,10#的最大冲蚀率出现在30°~45°区间,AISI304最大冲蚀率出现在30°。10#在30°,45°冲击角度下冲蚀磨损率会随温度上升显著上升,在15°冲击角度下冲蚀磨损率反而会随温度上升而下降。AISI 304在15°,30°,45°冲击角度下,冲蚀磨损率均会随温度上升而上升;在特定条件下,10#管材的冲蚀性能将优于AISI304。     

2016冬季京津冀一次持续重度霾天气过程分析

2016年12月16~21日我国京津冀地区发生了一次持续重度霾天气过程.为了进一步加深对霾的认识和提高对霾的分析预报能力,利用多种资料,对此次重度霾天气过程的环流背景和气象要素等进行了综合性分析.结果表明,此次过程持续时间长,污染强度大,影响范围广,能见度低,以外来输送为主,气溶胶主要分布在600 m以下高度,有一定的极端异常性,静稳天气指数与空气质量指数有较好的对应关系;京津冀地区高空受高压脊前的纬向环流控制,维持偏西气流,冷空气活动弱,以下沉气流为主,水汽含量较低,高空云量较少,低空有暖脊北伸,地面位于高压东南部,受均压场控制,气压梯度较小,受偏南风影响,污染物易于堆积;地面静小风,相对湿度较高,混合层高度较低,不利于污染物的水平和垂直扩散.     

Simulation of Reflected and Scattered Laser Radiation for Designing Laser Shields

This paper presents a computer simulation of reflected and scattered laser radiation for calculating the angle of laser shields performed with the Laser Shield Solver computer program. The authors describe a method of calculating the shield angle for laser shields which protect workers against reflected and scattered laser radiation and which are made from different materials. The main assumptions of the program, which calculates and simulates reflected laser radiation from any material and which can be used for designing shield angles, are presented. Calculations are compared with measurements of reflected laser radiation. The results for one type of laser and different materials which interacted with a laser beam showed that the Laser Shield Solver was an appropriate tool for designing laser shields and its simulations of reflected laser radiation distribution have practical use.     

地铁站内空气幕防烟效果的数值模拟研究

地铁站内站台层发生火灾时,站台层的烟气会通过站台层到站厅层的楼扶梯蔓延至站厅层。为了研究楼扶梯口处设置空气幕对站台层烟气的阻挡效果,进行了数值模拟研究。主要研究空气幕的出口风速,出口射流角度对烟气的阻挡效果。设置的空气幕风速有3m/s,4m/s,5m/s,10m/s;设置的角度有0°,15°,30°。通过模拟对比空气幕前后温度变化,得出风幕风速为4m/s或者5m/s时即可较好阻挡烟气。角度为15°的空气幕比0°和30°的空气幕挡烟效果好。     

EMC用V型人工电源网络的解析

本文分别对理想和实用的V型人工电源网络的阻抗(模和相位角)、隔离度进行计算和分析,并将其与某公司生产的ENV216型人工电源网络的测试参数进行比较,验证了ENV216型人工电源网络是完全符合标准要求的,加深了对电源端传导发射测试的理解。     

半空间中圆柱形夹塞物对入射平面SV波的散射解析解

采用Fourier-Bessel波函数展开法,给出了半空间中地下夹塞物对平面SV波的散射解析解。借助大圆弧面近似模拟水平地表,由连续性边界条件和自由地表条件建立方程求解。通过参数分析,讨论了夹塞物本身及入射波特性对地表位移的影响规律。研究表明:夹塞物附近地表位移放大效应显著,地表位移对入射SV波频率和角度的变化比较敏感。当埋深较深时,夹塞物的散射效应可以忽略。