岩体裂隙面形貌特征对其渗流特性的影响研究∗

岩体裂隙面的形貌特征直接影响其渗流特性,为了分析二者的相关关系,采用劈裂法制备了单裂隙砂岩试样,进行了裂隙面扫描分析和渗流试验,基于分形维数在定量表达不规则曲线形貌特征方面的优势,提出了考虑裂隙面形貌各向异性特征的分形维数计算方法。研究结果表明:(1)基于矩阵理论的裂隙面综合分形维数,相当于用矩阵网格去覆盖整个裂隙面,可以较好地反映裂隙面的整体形貌特征;(2)裂隙面的形貌特征对其渗流特性影响显著,随着裂隙面综合分形维数逐渐增大,裂隙岩体的渗透系数逐渐减小,而且侧向应力越大,渗透系数的减小趋势越明显;(3)分析建立了裂隙岩样渗透系数kf与裂隙面综合分形维数■的相关关系,验证分析表明,该公式计算得到的裂隙岩样渗透系数与试验结果吻合较好。相关研究成果可为裂隙岩体渗流特性分析提供参考。     

电极材料对脉冲等离子体降解有机废气的影响分析

用脉冲等离子体降解有机废气,对甲苯、二甲苯的降解率达73％～91％,对二氯甲烷的降解率达82％。在实验中发现电极材料的不同会影响分解效果,其中钨电极的降解率最高。本文运用等离子体化学中放电气体电子碰撞电离和化学自由基产生的机理以及阴极电子学中带电粒子轰击电极表面激发二次电子发射的理论,通过比较不同金属电极的二次电子发射系数δ,研究电极材料对脉冲等离子体降解有机废气影响的机理,发现主要是由于不同电极材料δ值的差异引起降解率的差异,电极稳定性对降解率和电极寿命也有重要影响。在实验的三种电极材料中钨的δ值最大,其最大二次电子发射系数δ_m为1.4,铜其次为1.29,不锈钢最小约为1.24,这成为导致三者降解率差异的主要原因。     

A generalized analytical solution for turbulent dispersion with inhomogeneous wind and diffusion coefficient

A technique is presented to solve analytically the turbulent diffusion equation for the concentration of a passive contaminant emitted from an elevated continuous source into the atmosphere. A generalized method of solution using Sturm–Liouville and WKB theories is developed to overcome difficulties due to the height‐dependent wind velocity and diffusion coefficient appearing in the diffusion equation. The method presented in this paper is able to derive an asymptotic expression for the concentration obtained from the solution of the atmospheric diffusion equation which involves explicitly inhomogeneous wind velocity and diffusion coefficient. The diffusion equation model derived from this method can be applied in a practical prediction of contaminant concentration in a turbulent atmosphere. This revised version was published online in August 2006 with corrections to the Cover Date.     

烧结烟气SCR脱硝系统的数值模拟及工程验证

对某钢厂烧结机增设的选择性催化还原（SCR）烟气脱硝系统进行了数值模拟优化及工程验证。将高温焦炉烟气喷入烧结烟气后,喷氨格栅入口平均温度提高了30 K,为催化剂层的SCR反应提供了较适宜的温度。采用分别在烟道弯头处和反应器主体入口处添加导流板的方法解决了烟气回流问题,SCR反应器第一层催化剂入口处速度最大偏转角降为8.2°,氨与NO_x摩尔比的标准偏差系数降至4.11%,SCR反应器脱硝率为82.6%,均达到技术标准要求。     

玉米酒精生产过程COD产污系数计算模型的建立

基于玉米酒精生产工艺流程,采用实测和物料衡算结合的方法,分析玉米酒精生产关联物料,并建立关联物质量平衡方程。实验测得绝干全玉米的COD负荷值为1611 mg/g,在此基础上推导出玉米酒精生产工艺的COD产污系数与淀粉出酒率、玉米淀粉含量、胚芽收率、玉米油收率、杂醇油收率和干玉米酒糟收率的量化模型。采用国内行业相关参数值代入模型进行核算,并与《第一次全国污染源普查工业污染源产排污系数手册》和《清洁生产标准酒精制造业》(HJ 581—2010)中的相关系数进行对比。结果表明:手册值在模型计算范围内;模型计算值略大于标准指标,与标准中一级COD产污指标基本一致。     

Traction performance across the life of slip-resistant footwear: Preliminary results from a longitudinal study

Introduction: Slips, trips, and falls are a major cause of injury in the workplace. Footwear is an important factor in preventing slips. Furthermore, traction performance (friction and under-shoe fluid drainage) are believed to change throughout the life of footwear. However, a paucity of data is available for how traction performance changes for naturally worn, slip-resistant footwear. Method: The presented research is a preliminary analysis from an ongoing, larger study. Participants wore slip-resistant footwear while their distance walked was monitored. Friction and under-shoe fluid pressures were measured using a robotic slip tester under a diluted glycerol contaminant condition after each month of wear for the left and right shoes. The size of the worn region was also measured. Results: Friction initially increased and then steadily decreased as the distance walked and the size of the worn region increased. Fluid pressures increased as the shoes were worn and were associated with increased walking distance and size of the worn region. Discussion: Consistent with previous research, increases in the size of the worn region are associated with increased under-shoe fluid pressures and decreased traction. These trends are presumably due to reduced fluid drainage between the shoe-floor interface when the shoe becomes worn. Conclusions: Traction performance changes with natural wear. The distance walked in the shoe and the size of the worn region may be valuable indicators for assessing loss of traction performance. Practical Applications: Current shoe replacement recommendations for slip-resistant shoes are based upon age and tread depth. This study suggests that tools measuring the size of the worn region and/or distance traveled in the shoes are appropriate alternatives for tracking traction performance loss due to shoe wear.     

基于激光雷达走航车的大气污染物探测技术及其应用

大气气溶胶对人体健康环境和全球气候都有一定的影响,是大气污染的主要来源。为了提升空气质量,大气污染防治刻不容缓。把气溶胶探测激光雷达和测风激光雷达集成在车辆上,进行走航和扫描探测可获得立体的大气气溶胶时空变化状态图。以合肥和芜湖等地大气气溶胶探测为例,基于激光雷达走航车的探测数据,获得大气气溶胶消光系数时空分布图,搜寻污染物排放源和估算颗粒物的PM_2.5输送通量。由此可知,激光雷达走航式探测技术是获得大气污染立体图像便捷的、有效的方法,可为大气污染防治提供精准的科学依据,具有重要的应用价值。     

基于模糊数学的大气环境质量综合评价

鉴于大气环境质量评价中客观存在的不确定性和模糊性,运用模糊数学方法,选用SO2、NO2、PM10作为评价因子,参照大气环境质量标准,通过计算污染因子权重分配系数和隶属度对乌鲁木齐市2004年至2010年大气环境质量给出客观的评价,综合评价结果表明乌鲁木齐市总体大气环境质量为轻度污染(三级),但空气质量在逐年好转,SO2和PM10依然是乌鲁木齐市空气质量的制约因子,且NO2的权重在逐年上升。模糊综合评判考虑环境空气质量评价的模糊性,根据污染物浓度对各级别的贴近度考察污染物的级别,评价结果比较直观,可以细致准确的评价环境质量等级,评价结果基本可以反映环境空气污染的情况。     

吸附剂浓度对Zn(Ⅱ)和Cd(Ⅱ)在高岭土上吸附的影响

研究了吸附剂浓度(Cs)对Zn(Ⅱ)和Cd(Ⅱ)在高岭土上吸附的影响。结果表明,随Cs增大,吸附等温线下降,呈现出明显的吸附剂浓度效应(Cs-effect)。采用经典Langmuir和Freundlich吸附等温式对吸附数据进行拟合表明,在给定Cs下,Zn(Ⅱ)和Cd(Ⅱ)的吸附等温线分别符合Langmuir和Freundlich等温式;但这2个等温式不能描述或预测Cseffect,模型参数与Cs有关,与模型理论预测相悖。为解释和描述固/液界面吸附中的Cs-effect,我们近期提出了表面组分活度(SCA)模型,并推导出了Langmuir-SCA和Freundlich-SCA等温式。采用SCA模型等温式对吸附数据进行拟合表明,Langmuir-SCA和Freundlich-SCA等温式可分别准确地描述Zn(Ⅱ)和Cd(Ⅱ)在高岭土上吸附的Cs-effect结果,证明SCA模型是合理的。     

不同处理技术对河流污染物降解系数影响的比较

以苏州官渎花园内河为研究背景,利用模拟河道分别考察了曝气复氧、人工水力循环、渗滤净化技术3种处理技术对受污河水中COD降解系数k COD、NH3-N降解系数k NH3-N变化规律的影响。实验表明,在无外源污染且河水滞留的天然情况下河道拥有一定自我净化的能力,并且3种处理技术对COD、NH3-N的降解系数都有一定提高,分别使k COD增加了34.3%、47.8%和57.8%,k NH3-N增加了8.35%、15.4%和52.8%,结果显示,渗滤净化技术对污染物降解系数的提高影响最大。