Albedo Measurements and Optical Sizing of Single Aerosol Particles

Aerosols play an important role in global climate change by their interactions with incoming solar radiation and outgoing longwave radiation from the planetary surface. The climate effects of aerosols depend on their scattering and absorption properties. This article describes the development of an instrument (ASTER: Aerosol Scattering To Extinction Ratio) that simultaneously measures the scattering and extinction of single aerosol particles. ASTER uses a high-Q cavity to amplify the extinction signal and innovative optics to collect the scattered light. It can distinguish many partially absorbing particles from a few black ones even if the bulk absorption is the same. Optical sizing and single-scattering albedo measurements were made for laboratory-generated particles with diameters from about 300 nanometers to above one micrometer. Using this prototype instrument, changes in albedo for single particles of 20% or greater were detected by measurement of the scattering and extinction. Optical sizing of the individual particles to within ～ 50 nm was accomplished using the ratio of the forward scattered light to the total scattering. Initial measurements of laboratory air showed a mode of highly absorbing particles. This article reports design and early laboratory tests on ASTER.     

Biologically-Directed Fractionation of Four Seasonal Extracts of Airborne Particulates and Related Chemical Studies

Ames assays (TA98) were applied toward assessing the mutagenic activities of extract fractions and subfractions of inhalable airborne particulate matter obtained in the manner of the earlier ATEOS study. Specifically, sequential cyclohexane, dichloromethane and acetone extracts of 24-hour samples were composited on a quarterly basis (ca 15 samples/quarter) and then fractionated using thin layer chromatography. For all four quarters the highest specific activities were associated with dichloromethane extracts and, specifically, its most polar fractions. Hydroxynitro-PAH are likely components in the dichloromethane extract. The cyclohexane extracts, containing PAH and nitro-PAH, were much less active. The acetone extracts had significant activity possibly associated with azaarenes and phenols. While PAH levels decreased in summer, nitro-PAH levels rose. No simple trend was observed for the PAH-quinones. 2-Nitropyren-1-ol, formed readily via solution photoxidation of 1-nitropyrene, does not appear to be formed under ambient atmospheric conditions. Preliminary FTIR, HPTLC and GC/MS results are described.     

Airborne Deployment of an Instrument for the Real-Time Analysis of Single Aerosol Particles

An instrument is described that provides real-time chemical analysis of the composition of individual aerosol particles. A differentially pumped aerosol inlet transfers particles from the ambient atmosphere into the source region of a time-of-flight mass spectrometer where they impact on a heated surface and the resulting vapors are ionized by electron ionization prior to mass analysis. Labora tory calibration studies demonstrated that the instrument was capable of detecting particles with diameters greater than approximately 0.4mu m. The instrument was operated on the NASA DC-8 research aircraft as part of the 1996 SUbsonic aircraft: Contrail and Cloud Effects Special Study (SUCCESS) mission with the intent of studying the chemical composition of upper tropospheric particles. More than 25,000 aerosol particle mass spectra were recorded during 19 mission flights. Although approximately 120 of those spectra showed clear evidence of sulfate, nitrate, and other inorganic materials, the remaining spectra contained only mass peaks consistent with water. Moreover, particles were detected only while traversing clouds. These results are not consistent with expectations of the size, quantity, or composition of upper tropospheric particles. It is likely, however, that a subisokinetic aircraft sampling inlet resulted in the collection of only very large ice particles. This situation would account for both the observed preponder ance of water-only spectra and the apparent lack of particles outside of clouds. Despite the sampling problem, the instrument was able to chemically speciate aerosols directly sampled from a medium altitude aircraft. These represent the first examples of aerosol particles chemically speciated in real time from an airborne platform.     

Simultaneous Detection of Positive and Negative Ions From Single Airborne Particles by Real-time Laser Mass Spectrometry

ABSTRACT

The instrumental setup used for simultaneous bipolar ion detection in on-line single-particle analysis by laser mass spectrometry is described. Particle size calibration has been performed using aerodynamic time-of-flight techniques. Mass spectra of several hundred ambient particles with aerodynamic diameters of 0.8 μm have been evaluated for statistical classification (Principal Components Analysis [PCA]) in order to identify main chemical components of the prominent particle classes.     

Airborne Phase Doppler Interferometry for Cloud Microphysical Measurements

Conducting accurate cloud microphysical measurements from airborne platforms poses a number of challenges. The technique of phase Doppler interferometry (PDI) confers numerous advantages relative to traditional light-scattering techniques for measurement of the cloud drop size distribution, and, in addition, yields drop velocity information. Here, we describe PDI for the purposes of aiding atmospheric scientists in understanding the technique fundamentals, advantages, and limitations in measuring cloud microphysical properties. The performance of the Artium Flight PDI, an instrument specifically designed for airborne cloud measurements, is studied. Drop size distributions, liquid water content, and velocity distributions are compared with those measured by other airborne instruments.     

A Personal,Thermophoretic Sampler for Airborne Nanoparticles

Engineered nanoparticles possess unique properties that present potential health risks to the workers who manufacture them and to consumers who are directly or inadvertently exposed to them. Monitoring personal exposures to these materials is necessary to evaluate such potential risks. A thermal precipitator was designed to measure concentrations of airborne nanoparticles in the breathing zone of exposed individuals. Particle collection efficiency was evaluated at flow rates of 5 and 20 mL/min and for particle sizes ranging from 15 to 240 nm. Particle transmission efficiency (with the temperature gradient off) and uniformity of particle deposition across the collection surface were also evaluated. Particle collection efficiency ranged from 100% at 5 mL/min flow to approximately 50% at 20 mL/min. Particle collection was generally homogeneous near the center of the collection plate over a distance of approximately 2 mm. Particle collection was less uniform near the edges of the collection plate, with a tendency for increased deposition near the inlet and flow centerline.     

Predictive Models for Deposition of Diesel Exhaust Particulates in Human and Rat Lungs

Diesel exhaust particulates are potentially hazardous when they are inhaled into the respiratory system. In this paper, theoretical models were developed to predict the deposition of such particles in humans and rats. It was shown that because of their submicron particle size, a significant fraction of diesel exhaust particulates can penetrate into the alveolar region of the lung and deposit there. Under normal breathing conditions, the alveolar deposition for humans was found to be between 7% and 13% depending upon particle size distribution. The alveolar deposition for rats was also investigated and it compared favorably with existing experimental data. Despite their considerable differences in airway size and respiratory condition, humans and rats exhibited similar deposition patterns during a breathing cycle; however, the average minute particle dose per unit pulmonary surface was found to be significantly higher for rats.     

水泥窑炉温度在线图像监测装置

水泥窑炉温度在线图像监测装置是特种应用电视监控系统,本系统可直观地监视高温窑炉炉料形状、烧成温度及工业料气流的分布等炉内工况,可实时地掌握和了解布料情况。历史视频图像可经过数字硬盘录像技术实现长时间保存,并可再行处理和测温,窑炉内实况视频信号经过数字化在线处理,可使料面的气流分布和温度分布状况以视频原始图像、伪彩色图像及数据和分布曲线图的形式实时呈现在显示器屏幕上,为操作和生产管理人员提供强有力的定量分析手段。该装置以其独特的耐高温设计,丰富的图形图像信息,完善的功能特性,长期稳定可靠的工作状态,对控制燃料气流的分布和改善高温窑炉运行状态,提高生产效率,保障安全生产,起到了十分重要的作用。     

Comparison of Cleanroom Samplers for Inorganic Airborne Molecular Contaminants

Abstract

The performances of inorganic airborne molecular contaminants (AMCs) via silica gel tubes, impingers, and diffusion denuder sampler (DDS) were compared in a cleanroom. The results showed silica gel tubes were not applicable for cleanroom sampling due to high blanks. While with optimal sampling conditions both impingers and DDS have much better performances, of which DDS has the lowest detection limits of the method for HF, HCl, HNO₂, HNO₃, SO₂, and NH₃ gases to be 0.15, 0.11, 0.13, 0.03, 0.07, and 0.42 µg/m³, respectively. Results indicated no significant difference for the HF and SO₄ ^2? concentrations made by the DDS and impingers.     

Generation of Airborne Multi-Walled Carbon Nanotubes for Inhalation Studies

Recent studies suggest that inhaled or intratracheally instilled multi-walled carbon nanotubes (MWCNTs) cause adverse health effects depending on the fiber length. In the present study a simple batch particle generation system was developed to generate airborne MWCNTs for inhalational toxicology studies. The generation rate can be controlled by the amplitude of sieve shaker. Maximum concentration of respirable airborne MWCNTs was 1.2 mg m^–3 at a nose-exposure chamber supplied with air at flow rate of 30 L min^–1. We examined the performance of airborne MWCNT generation system and characterized properties of generated fibrous particles at mass concentrations of 0.4 mg m^–3 (particle number; ca. 1700 cm^–3). Monomodal shaped size distributions with peak located at electrical mobility diameter of 300 nm (in number) and aerodynamic diameter of 1–2 μm (in mass) were measured with a scanning mobility particle sizer and with a low-pressure impactor, respectively. Two hour particle generation reproducibility tests were conducted five times, in which stability and repeatability of particle size and total number concentration were within an acceptable range. Aerodynamically classified particle morphology was studied by TEM, dissociated fiber-like and agglomerated MWCNT particles were observed. The former contributes up to 38% to counted particles, and the average width and length of fiber were 80 nm and 3.7 μm, respectively, with an aerodynamic size for particle of 260–381 nm.     

大型旋转设备状态监测系统的探讨

在分析设备故障诊断的基础上,对大型旋转设备状态监测系统进行了探讨;阐述了状态监测系统的要求、方案、研究内容、故障诊断方法、总体结构和软硬件构成,并介绍了状态监测技术在风机状态监测与故障诊断系统上的应用实例。     

FSY-3型腐蚀在线监测仪的开发

利用电化学的线性极化理论,以C8051F021微处理器为核心设计了硬件电路和软件,开发出高集成度、小型化FSY-3型腐蚀在线监测仪。利用单点自动连续测量实现了对金属的瞬时腐蚀速度的在线测量和对循环冷却水系统中金属腐蚀变化趋势的在线监测。利用串口通信实现了与计算机之间的数据交换,并结合计算机实现了数据记录及腐蚀曲线绘制等功能。同时通过D/A转换通道,实现了对循环冷却水系统的加药控制。     

同时消除柴油机尾气排放炭颗粒和NOx催化剂的研究进展

介绍了简单氧化物、复合氧化物(尖晶石和钙钛矿)催化剂都具有同时消除柴油机尾气中的炭颗粒和NO的活性．但是炭颗粒的起燃温度较高,生成N2的选择性差。在消除炭颗粒和氮氧化物时,有N2O生成,造成二次污染,炭颗粒与催化剂的接触形式直接影响炭颗粒的燃烧温度。     

新型钻井监测仪软件系统设计

介绍了钻井参数监测软件的结构体系、数据流程以及功能模型,并论述了软件系统中所处理的几个关键技术.     

气化炉火焰智能化检测系统

近年来,智能可视化燃烧测控技术成为燃烧领域研究的热点问题。针对粉煤气化炉内燃烧火焰图像的智能化检测,开发了同时具备火检、视频图像和温度预报三种功能的"三合一"气化炉火焰智能化检测系统。该系统无论在气化炉点火、升压还是投煤等工况波动阶段均能够表现出稳定的性能。目前已经在2 000t/d干煤粉气化炉中得到广泛应用。     

PVC生产过程性能监视及故障诊断

本项目基于多元统计分析理论,通过建立PVC生产过程的统计数学模型和故障诊断,利用计算机强大的计算功能和先进的非线性多方向主元分析故障诊断算法,解决PVC生产过程性能评价、故障检测和诊断问题。     

手持式监视器外壳塑件的结构优化设计

为减少电子产品因实物跌落碰撞试验造成的成本浪费并提高产品结构的可靠性,以手持式监视器外壳塑件为研究对象,基于Creo软件建立4组不同圆角、壁厚的三维模型,以ANSYS/LS-DYNA为仿真平台,分别进行自由跌落模拟试验。结果表明:4组结构中的两组圆角处的最大应力分别超过了屈服应力31.5%和14.0%;结构优化后的最大应力为189.466 MPa,比优化前降低了36.8%。根据仿真结果,3D打印出经过优化的实体模型进行实物跌落试验,结果显示,优化后监视器外壳跌落时发生的变形与仿真结果基本一致。     

机载雷达罩表面涂层的脱漆工艺研究

介绍了机载雷达罩表面涂层的脱漆方法,选用了能够在室温下脱除雷达罩表面耐雨蚀涂层体系的水基涂层脱除剂。通过试验研究了温度、时间对不同涂层脱漆效率的影响,并对基材的腐蚀速度进行了测定。