消除材料敏感性的电涡流传感器测量电路

被测材料的电磁特性会影响传感器的输出性能,限制其使用范围。为此,在分析阻抗投影变换原理的基础上,设计了一种能实现该原理的测量电路,用以消除传感器对被测材料的敏感性。11mm传感器输出测试实验的结果表明:所用7种被测材料经线性补偿后的输出特性曲线近似重合,可用一条直线替代,实现了消除材料敏感性的功能;计算出的传感器材料敏感性误差为±1.8%。     

沉淀法制备纳米氧化锌的研究

通过实验和理论分析 ,对均匀沉淀法和直接沉淀法制备纳米氧化锌进行了比较 ,以硝酸锌为原料 ,尿素为均匀沉淀剂制得的氧化锌粒径小、分布窄、分散性好 ,远优于直接沉淀法制备的纳米氧化锌。     

图像处理技术在稀相气固两相流粒度测量中的应用

利用高速摄影仪对冷态流化床内气固两相流动进行了图像采集.通过MATLAB软件对某时刻二维平面上的固体颗粒图像进行了预处理、二值化、粘连颗粒分割及颗粒标号等处理,较准确地得到了固体颗粒的粒度分布,并且研究了不同高度、不同截面颗粒的粒度分布与浓度分布状况,为今后进一步研究流化床内气固两相流动特性与粒度分布之间的关系奠定基础...     

颗粒定量测量的计算机图象处理技术研究

采用计算机图象处理、人工智能技术实现了对颗粒的定量分析,阐述了颗粒定量分析技术及原理、系统组成和软件设计。测试结果表明,该法操作简便、测试速度快、重复性好。     

Diffusion Sampler for Measurement of Acidic Ultrafine Particles in the Atmosphere

The adverse health effect of acidic ultrafine particles (AUFPs) has been widely recognized in scientific societies. These particles mainly deposit on the surface by diffusion and so far there is no mature method for the measurement of airborne AUFPs. The purpose of this study was to develop a diffusion sampler (DS) with iron nanofilm detectors to effectively measure the number concentration and size distribution of airborne AUFPs in indoor and outdoor environments. The developed DS was made of stainless steel with a flat and rectangular channel with 1.0 mm height, 50 mm width, and 500 mm length. The iron nanofilm detectors were deployed on rectangular recesses inside the sampler at three different locations along the length of the channel to collect the ultrafine particles. The exposed detectors were then scanned using an atomic force microscope (AFM) to numerate and distinguish the AUFPs from the nonacidic UFPs. Prior to sampling, the semi-empirical equations for the diffusive deposition efficiency of particles at the different detector locations in the sampler were obtained on the basis of theoretical diffusive mechanism and modified by the experimental data using polystyrene latex (PSL) standard particles. After calibration, the DS + AFM method and a commercially available online measurement system, i.e., scanning mobility particle sizer (SMPS) incorporated with a condensation particle counter (CPC), were simultaneously used in a 4-week field measurement. Both methods showed very good agreement in terms of total particle number concentration and size distribution. The results indicate that the diffusion sampler is effective for the quantification of ambient acidic ultrafine particles.

Copyright 2014 American Association for Aerosol Research     

Evaluation and Application of an Electrical Low Pressure Impactor in Disjunct Eddy Covariance Aerosol Flux Measurements

A micrometeorological application of an electrical low pressure impactor (ELPI) for the measurement of size-resolved particle fluxes between the surface and the atmosphere is proposed. Particles are introduced into the system for a very short time period through an inlet valve and analyzed in distinct size bins with the ELPI instrument for several seconds. Together with sonic anemometer measurements, size-resolved deposition velocities can be derived employing disjunct eddy covariance (DEC). Laboratory experiments studying ELPI instrument response indicate that a sampling interval of 0.3 s and a measurement interval of at least 5 s yield particle concentration data comparable to continuous sampling, and suitable for DEC. Calculations and Monte-Carlo simulations show that the finite length of the average period as well as Poisson and instrumental noise frequently introduce uncertainties in deposition velocities which may be an order of magnitude larger than the measurement value. In first field measurements with a prototype system, the measured fluxes were often below the detection limit as defined by the measurement uncertainties. At high particle concentrations, the DEC measurements could potentially extend current measurement capabilities to cover submicron particles fluxes in several size classes simultaneously.     

Effect of Neutron Flux on the Frequency Dependence of Permittivity of Nano Silicon Particles

In the present work, nano silicon is irradiated with a neutron flux (2x10 ¹³ n ?cm ^?2 s ^?1) up to 20 hours at different times. In the first stage frequency dependencies of real and imaginary parts of the permittivity of nanomaterials affected by neutron flux was analysed comparatively. As a result of this analysis it is known that the permittivity of nano silicon increases under the influence of neutron flux. The dependence of real and imaginary parts of permittivity of nano silicon particles is also reviewed. Moreover, the mechanism of the observed peaks and other effects is given in the work.     

In-Situ Measurement of Silica-Gel Coating on Particles of Alumina

Time-dependent growth of a silica layer on alumina particles suspended in a polymeric silica solution has been measured by monitoring the changes in the zeta potential of the alumina particles. There is an incubation period in the process, suggesting that the silica film forms by a nucleation-and-growth mechanism. The coated alumina particles are found to flocculate as their zeta potential approaches that of silica near its isoelectric point.     

Spectral Acquisition and Calibration Techniques for the Measurement of Radiative Flux Incident upon Propellant

A technique for the absolute calibration of a time‐resolved spectrographic system has been developed at QinetiQ, specifically designed to be relevant to spectral acquisition from within the interior of translucent gun‐propellant samples. The technique has shown itself to be particularly useful in the realm of propellant ignition as it allows for the precise determination of the moment that propellant combustion processes begin, as well as measuring the incident radiative flux leading up to ignition. Scope exists to extend its use for high‐pressure measurements of the incident radiative flux during both conventional propellant burn and high‐powered electrothermal‐chemical (ETC) discharges. This paper sets out to describe both the technique and some of the pitfalls encountered during the development of the technique. The use of this technique in some of the experimental work performed at QinetiQ, including the results of measurements that compare the incident radiative flux with propellant ignition during both ETC discharges and conventional gunpowder burn, have been published separately; references for this experimental work are given in this paper.     

热通量传感器在爆炸场热辐射测试中的应用

利用一种热通量传感器(HFM)测试系统研究了爆炸场的热辐射效应,测试了质量为27 kg的固液复合含铝炸药、固体复合含铝炸药、燃料空气炸药以及TNT4种炸药的爆炸场热效应,得到了相应的热通量动态曲线.依据云爆药剂的爆炸特性,分析了爆炸场的热效应以及热毁伤效应.结果表明,通过HFM可以获得明显的爆炸场热通量信号以及HFM的...     

X-Ray Measurement of Strain in Quartz Particles of Whiteware Bodies

Work on internal stresses in whitewares caused by differential thermal expansion of the crystalline and vitreous components is reviewed briefly. Thermoelastic strains in the quartz of four whiteware bodies containing mono-disperse quartz particles 2 to 4, 6 to 9, 20 to 27, and 44 to 54p in diameter, respectively, at concentrations of approximately 20 wt% were measured by X-ray diffraction. A high-temperature technique, involving measurement of dllo, d₁₁₀, d₂₀₁, and d₂₁₁ spacings at 25° and 650° C using Mo Kα, Cu Kα, and Fe Kα radiations, and a room-temperature technique using these radiations plus Cr Kα gave consistent results in agreement with theoretical predictions of the effect of nonuniformity of stress in particles near the sample surface. Strain determinations on powdered samples and changes in line shapes with temperature indicate that the measured strains were due to thermoelastic stress. The measured stresses were 4200 kg/cm² parallel to the quartz c axis and 5700 kg/cm² parallel to the quartz a axis. The stresses in the body containing the largest particle size quartz may be somewhat lower because of the formation of cracks.     

气溶胶单粒子成分和粒径的实时测量

利用气溶胶飞行时间激光质谱仪测定了两种芳香烃气溶胶的质谱,发现芳香族化合物产生的气溶胶粒子容易形成分子离子峰,对苯二酚还发生分子离子反应.对室内外空气中的气溶胶粒子的粒径进行实时检测的结果表明,室内外空气中的气溶胶粒子多以细粒子为主.实验结果表明,该仪器在大气气溶胶污染监测及相关研究领域具有重要的实用价值.     

PIV技术应用于循环流化床颗粒运动测试

粒子图像测速(PIV)技术被尝试用于测量循环流化床内颗粒运动,运用二值化互相关图像处理算法,得出了流场中粒子的轴向速度及水平方向速度分布图,并分析了粒子运动的变化规律。测试结果较好地反映了循环流化床内颗粒流动的一些特性,表明PIV技术在循环流化床气固两相流体特性研究中具有较好的应用前景。     

Measurement of the Aerodynamic Drag Force on Single Aerosol Particles

The “picobalance” (quadrupole) was used to measure the aerodynamic drag force on individual solid particles and droplets by suspending the object in a laminar jet of gas introduced through the bottom electrode. Particles ranging in diameters from about 1 to 150 μm can be studied in this manner. The DC voltage required to maintain the particle position against the opposing forces of aerodynamic drag and gravity was measured to determine the drag force. The flow velocity at which the aerodynamic drag force balances the gravitational force yields information on the aerodynamic size, and the DC voltage required to suspend the particle against gravity with no flow provides a measure of the particle mass. Particle mobilities for spherical and irregularly shaped solids are presented. Light-scattering measurements for spherical particles provide an independent determination of size; the results are generally in good agreement with the aerodynamic size. It is shown that the electrodynamic balance can be used to measure drag forces much larger than the particle weight.     

蓄电池槽体专用聚丙烯料的研制

为了替代进口树脂，本所立足国内原料，进行了蓄电池槽体专用聚丙烯料的研制。以洛阳石化总厂聚丙烯ＰＰＦ４０１粒料和粉料为基础，加入增韧改性剂、相容剂、成核剂等进行共混改性，并利用ＤＳＣ考察了专用料间的相容性、成核结晶性，并对力学性能进行了测试。试验结果表明：ＥＰＤＭ与ＰＰ相容性最佳，增韧效果最好；随着橡胶含量的增加，抗冲击性能明显提高，而体系的流动性和拉伸屈服强度变小；ＬＬＤＰＥ加入体系中，与橡胶起到了相互增容的作用，因而体系综合力学性能提高；成核剂的加入使体系结晶速度大大提高，结晶温度有所提高，力学性能也提高；流变分析表明专用料流动性好，可加工范围广。专用料性能达到了技术标准要求，经应用试验得到用户认可     

蒸汽蓄热器配套调节阀的选型与验证

根据蒸汽喷射试验系统的工作原理,从流量系数判定、阀型选择和阀体材料选择3方面研究了调节阀的选型方案,并从流量和噪声两方面对调节阀进行了验证,结果表明:基于所提方案选择的蒸汽蓄热器配套调节阀能够满足蒸汽喷射试验系统的工作要求。     

锂离子蓄电池的进展

锂离子蓄电池是新一代高比能量的化学电源。它电压高、自放电率低、循环寿命长、高低温性能好、使用安全。广泛用于移动通讯、笔记本电脑、数字摄录像机、微型存储卡等。并将用作电动车、家庭贮能、电网贮能大功率电源,以及用在航空、航天器上。     

高压蓄能器的设计

本文介绍了高压蓄能器设备的设计选材、强度计算及结构设计。人孔采用自紧式密封结构,并对密封垫提出了详细技术要求,为同类型高压设备设计提供了借鉴。     

Mass Measurement of Non-Spherical Particles: TDMA-ELPI Setup and Performance Tests

An ELPI was introduced to the TDMA setup for measurement of effective density and particle mass. This allows measurement of particle mass change also in cases when the particles are non-spherical or have voids. In addition to mass change of a particle, the density of transferred matter can be calculated if either unconditioned or conditioned particles are spherical and the bulk (material) density of the core particle is known. The performance of the system was tested by numerical simulations and laboratory experiments. According to the results, the smallest detectable particle mass change is approximately ± 17%. The measured density for the condensing species was within 15% of the bulk density value. Particle mass change caused by condensation of semi-volatile components of exhaust gas on diesel soot particles was also demonstrated.     

电涡流传感器前置放大器的设计

电涡流传感器检测导电材料时会产生微弱的电流信号,要实现测量的高灵敏度和稳定性,前置放大器抑制噪声、漂移是设计的关键。首先,建立放大器噪声模型找出主要噪声源,用带通滤波网络抑制宽带噪声;其次,选用直流负反馈放大器抑制增益漂移,超级伺服电路抑制直流电平漂移;最后,通过PCB板插孔铜镀层测厚仪的前置放大器进行电路理论分析、仿真和试验验证。试验结果表明:前置放大器能将微弱信号从噪声中分离出来,放大后信号电平足以进行后续的信号处理和显示,并满足信号电平分辨率在1μm以下的要求。