海洋混合悬浮颗粒对蓝绿激光的散射特性研究

激光在水下的传输很大程度上会受到海水中悬浮颗粒物的影响,而目前对于海洋中悬浮颗粒物光散射的理论研究大多是针对单一成分的悬浮粒子而进行的,但是在真实海洋中悬浮颗粒物都是以多种成分混合的颗粒群形式而存在的,因此研究真实海洋中混合悬浮颗粒物对蓝绿激光的散射特性具有重要意义。该研究选取了对蓝绿激光传输产生较大影响的浮游藻类植物、悬浮泥沙、碎屑、悬浮气泡和矿物质这五种常见的悬浮颗粒物作为研究对象,充分考虑真实海况中这五种悬浮颗粒物的不同混合情况,构建了海水中混合球形悬浮颗粒物对蓝绿激光的散射特性模型。数值计算了海水中五种物质混合的球形悬浮颗粒物对532 nm蓝绿激光的统计平均光散射参量和平均散射相函数,分析不同混合悬浮颗粒物的混合比对平均散射、吸收和消光系数以及单次反照率随着粒子有效半径和粒子数浓度变化的影响,同时分析了不同粒子尺寸下的不同混合比对混合悬浮颗粒物的平均散射相函数随着角度变化的影响。数值结果表明,当悬浮泥沙在整个混合模型中占比越大时,平均散射系数越大,而当悬浮藻类粒子在整个混合模型中占比增大时,平均吸收系数增大,由此可知海洋中对光造成主要影响的五种常见悬浮颗粒物中,悬浮泥沙对光散射作用影响最大,悬浮藻类粒子对光吸收作用影响最大。随着悬浮颗粒物浓度的增大,混合粒子的单次反照率保持不变,由此可知混合悬浮颗粒物的平均光散射参量随着粒子浓度的增长速率是一致的。海洋中混合悬浮颗粒物的平均散射相函数随着粒子的有效半径的增大而增大,散射作用最大的混合比下的悬浮颗粒物其平均散射相函数最大,悬浮颗粒物的前向散射较强。该工作对蓝绿激光在海水中传输、信道建模,水下无线光通信的研究以及激光探测都具有重要的理论指导意义。     

大气漂尘中苯并[a]芘的简单同步荧光测定

通过选择合适的能量差(Δ-υ=1 400 cm-1),建立了大气漂尘中苯并[a]芘的恒能量同步荧光分析法。苯并[a]芘在甲醇与十二烷基磺酸钠(SDS)溶液中均有良好的线性关系(R>0.999),检出限分别达到1.34 nmol/L与0.40 nmol/L。该法亦可应用于18种多环芳烃混合物中苯并[a]芘的鉴别。     

Chemical Imaging for PAH Analysis in Particulate Materials

Abstract

Chemical imaging is a new analytical science, related to a combination of spatial and chemical resolutions. Several new chemical imaging tools have been developed and applied to environmental analysis. The advantages of such methods, which provide simultaneous morphological/geometrical and chemical speciation, are pointed out and exemplified in several environmental analytical applications. These include fast analysis of PAH contaminated aerosols at low concentrations, analysis of contaminated quartz sand particles, as well as improvement of laser induced fluorescence detection of PAH compounds in natural water, in the presence of various microparticles. It is shown that chemical imaging has a considerable potential in environmental applications and can provide detailed and unique information when particulate materials are concerned.     

Tefluthrin Sorption to Mineral Particles: Role of Particle Organic Coatings

Abstract

The sorption of tefluthrin was studied on “pure” clay minerals and those that had been coated with aquatic humic substances over a mass percent carbon range of 0.02 to 2.15. Tefluthrin sorption onto humic-coated minerals was significantly greater than on to the clean minerals and increased with increasing quantities of sorbed humic substances. Humic acid, the most aromatic coating, was the strongest sorbent, followed by fulvic acid, hydrophilic macromolecular acid and natural coatings on estuarine suspended particles. This shows the significant impact of humic coatings on the sorptive capacity of mineral particles. The sorption was linear, also consistent with the operation of a partition process. The partition coefficient normalised to organic carbon (K_oc) after deduction of the contribution from the clean mineral, ranged from 120000 to 770000 and was highest for the most aromatic humic acid fraction.     

Chemical Analysis and Toxicity Tests of Organic Pollutants in Xi River Water and Suspended Sediment of Shenyang City

Abstract

In 1987, in a 10-day investigation, two kinds of raw water and their suspended sediment samples were successively collected from the upper and middle reaches of the Xi River. The water and the suspended sediment samples were prepared by filtration of the raw water through a 0.45 μm membrane. The pH values of the water samples were adjusted to neutral (pH 6.5), basic (pH 11.0) and acid (pH 2.0) and passed through three adsorption columns filled with GDX macroreticular resin (MRR). The organic pollutants were subsequently eluted from the columns with CH₂Cl₂. Suspended sediment samples were extracted with CH₂Cl₂ by Soxhlet extraction. Organic pollutants were separated on silica gel columns and analyzed by GC and GCMS and assayed for acute toxicity, Ames test response, and micronucleus test response. Over 200 organic pollutants in the river water and the suspended sediments were determined. More than 60 main pollutants were identified according to the results of the chemical analysis and toxicity tests.     

超声浸取预处理-流动注射火焰原子吸收法测定大气颗粒物中Pb和Cd

本文提出超声波震荡前处理方法提取大气滤膜样品中待测金属。通过对样品浸取液种类、酸度和干扰方面的研究,确定了颗粒物样品溶液制备的最佳分析条件,结合流动注射在线富集——原子吸收技术,建立了环境中气体样品测定Pd,Cd方法。方法快速、准确,标准样品测定回收率在97％以上,六次测定相对标准偏差小于2.6％。     

纳米Al2O3和Fe2O3填充尼龙PA1010的摩擦磨损行为

采用模具挤压成型方法制备了纳米Al2O3和Fe2O3填充PA1010尼龙复合材料，采用MM-200型摩擦磨损试验机考察了所制备的尼龙复合材料在干摩擦条件下同45#钢对摩时的摩擦磨损行为。研究结果表明，填充纳米Al2O3使得PA1010尼龙复合材料的摩擦系数增大，而填充纳米Fe2O3使得摩擦系数降低；纳米Al203和Fe2O3填充尼龙复合材料的耐磨性能优于尼龙；当纳米填料的质量分数从10％提高到20％时，纳米Fe2O3填充尼龙的磨损量增大，纳米Al2O3填充尼龙的磨损量无明显变化，2种填料填充尼龙复合材料的摩擦系数变化不大．纳米Fe2O3填充尼龙复合材料同45#钢对摩时主要呈现粘着磨损和轻微疲劳磨损特征，而纳米Al2O3填充尼龙复合材料呈现脆性疲劳开裂特征。纳米Fe2O3填充尼龙复合材料在偶件磨损表面形成的转移膜更加均匀和连续，故其减摩抗磨性能优于纳米Fe2O3填充尼龙复合材料。     

静电悬浮转子微陀螺再平衡回路设计

给出了一种基于MEMS技术的静电悬浮转子微陀螺,可同时测量两轴角速度和三轴线加速度,采用力平衡原理测量壳体输入的角速度,即对转子实行闭环控制使转子保持在零位,输出控制电压反映壳体输入角速度的大小。在分析转子所受力矩的基础上,建立了转子的力矩平衡方程。当陀螺工作在理想状态下,提出了两种再平衡回路设计,即只采用校正环节和采用解耦网络的自平衡回路设计。通过系统仿真表明了采用解耦网络设计的再平衡回路的优越性。当壳体输入阶跃角速度时,解耦控制具有响应速度快、超调小、动态性能好等优点。最后给出了采用积分电路和加法运算电路实现解耦控制的电路实现方案。     

The distribution of solid particles suspended in a turbulent flow: A stochastic approach

Basic fluid mechanics and stochastic theories are applied to show that the concentration distribution of suspended solid particles in a direction normal to the mean streamlines of a two-dimensional turbulent flow is greatly influenced by the lift force exerted on them in the vicinity of the wall. Analytic solution shows that, when the direction of the mean flow is horizontal, the probability density functionp (y, t) for random displacements of the particles will have a maximum value at a point from the wall where the perpendicular component of the lift force precisely balances particle gravity. Interpretation of experimental observations is presented using this theory.     

MBBR两种填料对养猪废水脱氮除磷效果对比

为了探讨移动床生物膜反应器中不同填料对废水脱氮除磷效果的影响,采用碳纤维球和聚乙烯塑料两种不同悬浮填料进行对比试验。在不同运行条件下,分别测定氨氮、总氮、总磷、COD等指标,对比挂膜和脱氮除磷效果。结果表明,碳纤维球填料挂膜速度快,在不同运行条件下均比聚乙烯塑料填料对COD、NH4+-N、TN、TP等的去除效果好,去除率分别可达91.2%、98.0%、77.5%、68.1%。这说明比表面积大、孔隙率高的填料挂膜更快,挂膜量更多,更有利于实现同时生物脱氮除磷。