PM2.5颗粒物采样器校准装置设计及技术关键

正一、研究的目的意义PM2.5是指大气中直径小于或等于2.5微米的颗粒物,也称为可入肺颗粒物,也将PM2.5等同于气溶胶。所谓的气溶胶、细颗粒物其实就是指大气中直径小于或等于2.5微米的细颗粒物,简称PM2.5。虽然PM2.5只是地球大气成分中含量很少的组分,但它对空气质量等有重要的影响。研究表明,颗粒越小对人体健康的危害越大。气象专家和医学专家认为,由细颗粒物造成的灰霾天气对人体健康的危害甚至要比沙尘暴更大。粒径10微米以上的颗粒物,会被挡在人的鼻子外面;粒径在2.5微     

基于显微图像处理PM2.5尺寸的分布研究

了解大气中PM2.5颗粒物的大小分布对人体健康的影响有重要意义,本文中分析了大气颗粒物的图像特征,图像的识别和处理方法,用提取颜色通道、直方图均衡化、有选择保边缘平滑、开闭操作以及阈值分割等处理,分割图像中的颗粒,并有效地识别和分类颗粒物的大小;并在Image-Pro Plus 4.0(IPP)软件平台上实现了这一图像处理过程,这种处理和识别方法为PM2.5和其他微米、亚微米颗粒材料的图像分析提供了参考.     

金属基复合材料凝固界面颗粒行为的研究进展

综述了凝固界面与异相颗粒相互作用的理论模型及实验验证状况，并介绍了利用金属基复合材料进行研究的新进展。     

大气颗粒物在多孔材料上的吸附特性分析

PM2.5对大气环境及人类健康造成了较严重的危害,对PM2.5有效脱除净化技术的研究迫在眉睫。主要阐述了PM2.5与吸附相关的理化特性,对其在多孔吸附材料上的主要吸附力进行了探讨,表明颗粒越小,与固体表面距离越近,所受到的吸附力越大,颗粒所受吸附作用越明显;此外,吸附材料种类、空气湿度与压力亦为重要的影响因素。使用多孔材料对空气中的细颗粒物进行吸附过滤实验,并进行了简要分析。     

放射性气溶胶同时荷电-凝并模型的开发

放射性气溶胶发生衰变时会引起表面电荷累积，带电颗粒间发生静电相互作用，影响气溶胶的演化和迁移。为了探究颗粒荷电对气溶胶凝并行为的影响，从气溶胶荷电-凝并机制出发，建立完整的荷电-凝并双变量群平衡方程，使用分区法和单元平均技术数值求解。开发适用于放射性气溶胶发生的荷电-凝并行为的计算模型，使用近似解析方法和经典实验进行验证分析。结果表明：荷电-凝并模型能够准确预测与放射性气溶胶同时发生的荷电-凝并行为，对颗粒荷电对凝并动力学行为的直接影响进行阐释。     

一维声子晶体的振动特性与实验研究

研究了铝/橡胶一维声子晶体的机械滤波特性.采用有限元和传递矩阵法导出了弹性波在一维声子晶体中传播的理论模型.对声子晶体的振动传输与隔振特性进行了实验研究.研究结果表明：铝/橡胶一维声子晶体存在振动带隙,改变单元的几何尺寸和材料特性,能将带隙频率范围扩大并延伸至低频;实验验证了理论模型的预测,为铝/橡胶声子晶体在发动机隔振控制上的应用提供了依据.     

铁粒子多分散系统磁流变液的制备和性能研究

磁流变液是铁磁性颗粒分散到低粘度的油中形成的稳定的悬浊液。其扩散特性主要由颗粒本身的物性和颗粒间的相互作用而决定。为了更好的控制颗粒间的相互作用,我们加入同样物性,但尺寸更小的颗粒,以调控悬浊液的流动特性。研究显示,在高体积百分比的磁流变液中加入亚微米尺寸的铁颗粒可以显著改善流体在没有外加磁场情况下的流动特性。受范得华力影响,加入的小颗粒首先附着在大颗粒周围,形成组装体,组装体间范得华力较小,从而有效降低了流体粘度。流体的粘度随着小颗粒在大颗粒上附着的比例不同而变化。随着小颗粒的增加,流体中铁颗粒的体积百分比增加,从而提高了磁流变液在磁场中的屈服应力,增强了磁流变液的磁流变效果。     

超临界氦增压与排放过程的压力温度特性

为了探讨超临界氦增压技术在中国运载火箭和航天器上实现的可行性,进行了超临界氦增压排放实验研究。分析了低温杜瓦内的超临界氦的热分层稳定性;讨论了温度计引线两端大温差引起热声振荡和漏热现象;此外,由于节流微分效应和换热器管壁轴向导热,换热器出口温度在排放过程出现大幅温度波动。实验结果证明超临界氦增压过程中增压压力平稳、可靠,压力容易控制。但后续改进实验中应消除换热器节流微分效应导致的出口温度波动,并且减小杜瓦以及支撑结构的漏热。     

“海底山”地形的水下声传播分析

在声传播测量中,在测线上水深的较大变化,使声传播损失发生显著的变化。海底山和海底凹陷地形对声波的传播有较大影响,使声传播损失出现变大和变小的情况,甚至产生较大的声影区效应,对水声装备的研制和使用有重大影响。对一种特殊海底山地形下的声传播问题进行分析,并结合实验数据对比有无海底山情况下的声传播损失,期望对海洋环境测量和水下武器装备的研制及应用有所启发。     

烟道凝聚器流场及细颗粒凝聚特性研究

为研究烟道凝聚器的凝聚机制及颗粒物减排特性,通过商业计算流体力学（computational fluid dynamics,CFD）软件,模拟并得到了凝聚器湍流区定常/非定常工况条件下的流场特性;理论计算了凝聚器内颗粒的凝聚过程,并通过扫描电镜进行了验证;实验室中凝聚器对PM2.5的减排幅度为20.8%,实际工程中,300 MW和660 MW机组PM2.5的减排幅度分别为30.1%和37%。研究结果可为颗粒凝聚技术的大规模工程应用提供参考。     

细颗粒物声波团聚的微观机理研究

为拓展声波团聚机理,对声波团聚过程中的声流与声涡作用进行了理论和实验研究。利用声流测试系统,发现在0～1 kHz低频与5 kHz高频时,团聚室内声流现象较为明显;并通过可视化测试,在7 kHz高频时观察到明显的漩涡。结果表明,流场中的声流与声涡对颗粒团聚会产生很大的影响,声流或声涡越强,团聚效果越好。在0～1 kHz低频与5 kHz高频时,声流产生的切应力带动气溶胶颗粒发生碰撞团聚;高频时声涡力矩较大,其产生的轨道角动量带动粒子发生圆周和自旋运动;当声压级大于132 dB时,声涡团聚开始发挥作用,与声流一起促进颗粒团聚,且声压级越大团聚效果越强;与波节相比,波腹处的声流速度更大,声涡现象更明显,团聚效果也更好。     

Characterization of Dust Particles Emitted Through Pulse-Jet Fabric Filters During Industrial Pollution Control

The present investigation elucidates the role of pulse-cleaning parameters and filter media designs on the extent of dust emission and emitted particle characteristics during industrial pollution control using the pulse-jet filtration process. The study is followed by statistical analysis based on L₈ (2⁷) orthogonal design methodology. The experimental study shows that the dust concentration in clean gas increases with an increase in pulse pressure and pulse duration, whereas it decreases with an increase in pulse cycle. However, the contribution of pulse pressure and pulse duration is much higher than the impact of pulse cycle. In regard to the impact of filter media design, a higher level of bag height (which also implies lower air-to-cloth ratio) and lower level of seamline spacing can lead to higher outlet emissions at the transitory stage. The role of pulse pressure, bag height, and seamline spacing are found to be very significant in regulating fine particles in the emission (PM_2.5) and, consequently, the aforesaid factors affect all volume particles diameters (D₁₀, D₅₀, and D₉₇) and weight mean particles diameter D (4, 3) of particles in bulk.     

Modelling and experimental study on agglomeration of particles from coal combustion in multistage spouted fluidized tower

An experimental platform of spray agglomeration has been designed and built for removing small fly ash particles (PM₁₀) from coal combustion. Agglomerating model of fine particles during the spray process was developed by combining rapid coagulation theory and analysis of the interaction between droplets and particulates. Systematic experiments were conducted in multistage spouted tower using several kinds of agglomerant solutions. The influencing factors such as surfactant, pH value, flow rate of agglomerant solutions and inlet flue gas temperature were analyzed. SEM was used to analyze the microstructure of the aggregation. Based on this model, coagulation rate constant was calculated and the influences of original parameters were observed. The spray agglomeration mechanism of particles can be analyzed from both macroscopical and microcosmic aspects. Preliminary results are presented and discussed in this work. Final results indicate that the special shape of multistage spouted fluidized tower has significant influences on the effect of agglomeration. The findings from this work will be helpful to form the basis and provide guidance for further studies on the control of fine particles such as PM_2.5 or even smaller ones.     

Theoretical analysis of acoustic and turbulent agglomeration of droplet aerosols

This study meticulously explores the agglomeration mechanisms in microscale droplet aerosols, specifically focusing on acoustic and turbulent agglomeration mechanisms. Our theoretical analysis reveals a significant impact of orthokinetic and hydrodynamic processes on acoustic agglomeration. The acoustic wake effect elucidates the swift replenishment of small particles subsequent to an orthokinetic phase. An optimal frequency, varying for different droplets, was identified in orthokinetic agglomeration within the 50–250 Hz range. Hydrodynamic agglomeration remained relatively stable at an acoustic frequency exceeding 1000 Hz. The aggregation kernel function, denoted as K_ij, exhibited a significant increase with increasing sound pressure levels, reaching up to 10⁻⁸ s⁻¹. Environmental temperature had a predominantly positive effect on orthokinetic and Brownian agglomeration, although it exhibited an inhibitory effect on hydrodynamic agglomeration. For raindrops, a correlation was identified between particle spacing and K_ij; a larger particle spacing corresponded to a smaller K_ij. Despite an increase in particle spacing to 50 times the particle diameter, the hydrodynamic effect persisted. The aggregation kernel function linked to Brownian thermal motion was found to be 3–4 orders of magnitude lower than that of orthokinetic and hydrodynamic interactions. Additionally, the turbulent agglomeration kernel function for fog, cloud, and rain droplets with corresponding parent nuclei of 100 μm was of the same order of magnitude as the acoustic agglomeration kernel function.     

燃煤细微颗粒物声波团聚的机理研究

采用数值模拟的方式,对声波团聚中的同向团聚机理、流体力学作用机理以及布朗作用团聚机理等分别做了深入研究.模拟中选取四组具有代表性的颗粒粒径,分别从声波频率、声场强度、颗粒粒径、颗粒间距以及温度五个方面模拟计算.计算结果表明:同向团聚机理下存在一个最优团聚频率带,随着声压级的升高团聚效果也增强;较大的团聚颗粒存在一个粒径比其小的最佳团聚颗粒粒径;相同条件下,同向团聚机理所产生的团聚效果最明显,其次是声波尾流效应,其他的团聚机理相比前者影响较小.研究发现在某些特定因素影响下,声波尾流效应会强于同向团聚,说明了其在声波团聚过程中的重要性.     

光学互相关测速在声发射测粒中的应用

声发射测粒方法是通过测量分析粉体颗粒碰撞某个平面产生的声发射信号脉冲波形来荻取粒径分布信息的,为了获知颗粒的碰撞速度和粉体材料的声学参数,本文中尝试将光学互相关测速与声发射测量相结合,设计了同时测量自由落体颗粒碰撞平板的瞬时速度和声发射信号脉宽的实验。初步实验结果表明:光学互相关测速可以为声发射信号分析提供必要的信息。     

Vertical Profile of Particulate Matter Concentrations in Indoor Air (Case Study: Karaj,Iran)

Particulate matter is one of the most significant pollutants in indoor environments. The study of vertical profile concentration coefficients of different particulates leads us to figure out the most accurate pattern of vertical profile change of these hazardous particles. In this case, three different sizes of particulate vertical profile patterns, PM_1.0, PM_2.5, and PM₁₀, were evaluated in indoors in the city of Karaj. Samplings of first and fourth floors of 5 buildings located in different areas of Karaj were conducted constantly during 2011. The results of Mahestan Station illustrate the highest average concentration of PM₁₀ (173 µg/m³) whereas the RajaieShahr Station measurements indicates the highest average concentrations of PM_2.5(66 µg/m³) and also PM_1.0(51 µg/m³). Generally, the concentrations of the particulates in the first floors were higher than that in the fourth floors, and according to the air evaluation stations, all the particulates including PM_1.0, PM_2.5, and PM₁₀ had concentrations higher than the annual standard.     

介质扰动对声波的调制效应-参量接收阵及其他

文章从Lighthill方程出发,对介质扰动产生声传播非线性效应的国内、外研究情况进行了综述性介绍,重点介绍声波在被声场中同时存在的另一声波所扰动的介质中传播而产生的所谓“声散射声”现象,特别是由此而衍生的参量接收阵的理论、试验以及应用情况。绝大多数关于参量接收阵的理论和实验研究,都是着眼于其在小的径向(垂直于声传播方向)孔径条件下实现低频窄波束接收的特性,但这篇文章主要关注利用参量接收阵实现低频高增益接收的理论和试验研究;除重点介绍了国内、外的试验情况外,还特别关注将参量接收阵进行工程应用时面临的关键技术难点以及可能的解决思路。此外,文章还针对另一种介质扰动对声传播的调制效应,即“流散射声”,以及国外与此有关的工程应用、特别是苏联进行的号称超远程探潜应用进行了介绍和分析。     

统计最优柱面近场声全息识别声发射源研究

植物在受到病害胁迫时会发出声发射信号。通过声发射信号的采集,以统计最优柱面近场声全息技术为理论依据,进行植物的声源信号识别和声场分析。对单声源和多声源分别进行了仿真分析,通过不断修改全息柱面半径、重建柱面半径和测量点间距等参数,探索获得最佳重建效果的参数范围,同时探讨了窗函数对重建效果的影响。将基于统计最优算法的柱面近场声全息与基于空间傅里叶变换算法的柱面近场声全息进行了比较,仿真结果表明,单声源时基于空间傅里叶变换技术计算的重建面声压幅值相对误差均在10dB以下,而统计最优柱面声全息技术计算的重建面声压幅值相对误差均在15dB以下,多声源时基于空间傅里叶变换技术计算的重建面声压幅值相对误差基本在2dB左右,而统计最优柱面声全息技术计算的重建面声压幅值相对误差在26dB以下,充分表明了统计最优柱面声全息技术的优越性。     

Meteorological variations of PM2.5/PM10 concentrations and particle-associated polycyclic aromatic hydrocarbons in the atmospheric environment of Zonguldak, Turkey

Airborne particulate matter (PM_2.5 and PM₁₀) concentrations were measured in Zonguldak, Turkey from January to December 2007, using dichotomous Partisol 2025 sampler. Collected particulate matter was analyzed for 14 selected polycyclic aromatic hydrocarbons (PAHs) by high-performance liquid chromatography with fluorescence detection (HPLC-FL). The seasonal variations of PM_2.5 and PM₁₀ concentrations were investigated together with their relationships with meteorological parameters. The maximum daily concentrations of PM_2.5 and PM₁₀ reached 83.3 μg m⁻³ and 116.7 μg m⁻³ in winter, whereas in summer, they reached 32.4 μg m⁻³ and 66.7 μg m⁻³, respectively. Total concentration of PM₁₀-associated PAHs reached 492.4 ng m⁻³ in winter and 26.0 ng m⁻³ in summer times. The multiple regression analysis was performed to predict total PM_2.5- and PM₁₀-associated PAHs and benzo(a)pyrene-equivalent (BaPE) concentrations with respect to meteorological parameters and particulate mass concentrations with the determination coefficients (R²) of 0.811, 0.805 and 0.778, respectively. The measured mean values of concentrations of total PM_2.5- and PM₁₀-associated PAHs were found to be 88.4 ng m⁻³ and 93.7 ng m⁻³ while their predicted mean values were found to be 92.5 ng m⁻³ and 98.2 ng m⁻³, respectively. In addition, observed and predicted mean concentration values of PM_2.5-BaPE were found to be 14.1 ng m⁻³ and 14.6 ng m⁻³. The close annual mean concentrations of measured and predicted total particulate related PAHs imply that the models can be reliably used for future predictions of particulate related PAHs in urban atmospheres especially where fossil fuels are mainly used for heating.