首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 140 毫秒
1.
PCS纳米颗粒粒度测试装置的研究   总被引:1,自引:0,他引:1  
介绍了光子相关谱技术(PCS)测量纳米颗粒粒度的基本原理和PCS纳米测量装置的基本组成。因为纳米颗粒散射光所呈现的光谱是由颗粒粒径决定的,所以在纳米颗粒粒度测量中,单一角度测量只能观测到样品的部分情况。为了充分保证检测样品的真实表征及提高信噪比,文中提出了一个将步进电机和光纤联合应用于纳米颗粒粒度测量的设计方案。采用这个方案可以准确和方便地在不同角度上进行纳米颗粒粒度测量,而且有效地提高了信噪比和减小了装置的体积。  相似文献   

2.
PCS亚微米及纳米颗粒粒度测量仪的研制   总被引:5,自引:1,他引:4  
介绍一种利用光子相关光谱技术进行亚微米及纳米颗粒粒度测量的PCS粒度仪的工作原理和设计。  相似文献   

3.
田慧欣  彭晓  朱新军  孟博 《光学精密工程》2016,24(11):2814-2820
考虑传统动态光散射颗粒粒度分布测量用的反演算法复杂、精度不够、抗噪能力差,本文基于大数据思想,提出了一种动态光散射颗粒分布软测量方法。该方法通过调节颗粒粒度分布形状参数获得大量自相关函数及其对应颗粒分布的数据;使用这些数据对子学习机进行训练。最后,针对训练数据维数较高的特点对传统Bagging算法进行改进,并利用改进的Bagging集成算法集成子学习机以提高软测量模型的精度及泛化能力。通过模拟单峰数据和对300nm标准粒径进行软测量开展了验证实验。结果表明,该方法能够较好地测量出不同动态光散射颗粒分布的峰值及分布宽度,模拟单峰数据测量峰值精度可达1nm,300nm和503nm,标准粒径测量精度分别可达3nm和4nm,优于一般的反演算法。该软测量方法为动态光散射颗粒分布测量开辟了新的途径。  相似文献   

4.
PCS颗粒测量技术中数字相关器的研究   总被引:1,自引:0,他引:1  
林科  黄廷磊 《仪器仪表学报》2006,27(Z1):174-176
数字相关技术是纳米颗粒测量技术中的一个关键环节,自相关函数的估计质量直接影响颗粒测量结果.PCS理论较为复杂,数据运算量大,因此实现较为困难.文中介绍光子相关光谱法的基本原理,讨论数字相关器的内部结构,最后提出实现数字相关器的新方法,该方法计算精度较高,系统实现灵活,满足对光子相关光谱法中相关函数计算的高精度、实时性的要求.  相似文献   

5.
超声衰减法测量颗粒粒度大小   总被引:1,自引:0,他引:1  
提出一种基于两个频率下超声衰减系数测量,并结合ECAH超声衰减模型得到悬浊液中颗粒平均粒径的方法.并通过对亚微米范围的钛白粉悬浊液在1和2MHz频率下进行测量.测量结果与消光法测量进行对比,表明该方法应用到颗粒粒度大小测量是切实可行的.  相似文献   

6.
一、引言感光胶片的颗粒度是胶片的重要性能之一,颗粒噪声是光信号传递过程中噪声的重要来源。在光学信息处理中,特别是白光信息处理中,人们对感光胶片的颗粒噪声都给予了足够的重视。测量感光胶片的颗粒度,或测量光学噪声的空间频谱(Wiener 频谱),已有几种不同的方法:如用显微密度计扫描曲线的计算求解法,光学自相关方法,夫琅和费衍射方法等等。与人的视觉感受较为一致的尚有较通用的均方根颗粒度(RMS 颗粒度)的方法。均方根颗粒度R 的定义为:  相似文献   

7.
测量多峰分布模式颗粒尺寸的一种计算方法   总被引:2,自引:0,他引:2  
散射式激光测粒仪在微小颗粒的粒度分析中国用途广泛。本文提出一种基于该类仪器的用于测量多峰分布模式颗粒粒度的计算方法,即Row方法与多峰分布模式的组合算法。大量的计算机模拟计算和实测证实了这种算法的有效性和实用性。  相似文献   

8.
PCS颗粒测量技术中软件相关方法的研究   总被引:13,自引:2,他引:11  
数字相关是PCS颗粒测量技术中的一个关键环节,自相关函数的估计质量直接影响颗粒测量的结果。自相关函数的估计可以通过硬件或软件方法得到。在软件数字相关方法中,利用相关计算时可以得到全部的采样数据这一与硬件相关所不同的特点,能去除采样数据中的均值,并在分析偏差的基础上,采用无偏估计,可有效地提高信噪比,从而获得更好的相关估计值。  相似文献   

9.
钻井振动筛固相颗粒运动规律   总被引:3,自引:0,他引:3  
固相颗粒的运动规律对钻井振动筛的处理量有很大的影响。用固液两相流动理论和紊流理论研究了固相颗粒在淹没状态下的悬浮运动和推移运动规律;建立了钻井液悬浮粒度的计算公式;讨论了固相颗粒实现抛掷运动和悬浮运动的条件,并对起跳后的固相颗粒在钻井液中的运动情况进行了分析。实例计算表明,钻井液沿筛面流动时,沿程各断面处所能悬浮颗粒的粒度是有限的。那些小于悬浮粒度的固相颗粒,将在紊流垂直脉动速度的作用下,作悬浮运动;而那些大于悬浮粒度的固相颗粒,将沉降在筛面上,然后随液流以滑动、滚动及抛掷跳跃的形式运动;且作抛掷跳跃运动的颗粒跳不出钻井液层。固相颗粒的悬浮运动和推移运动,有利于钻井液透过筛网,从而提高筛网处理液相的能力。  相似文献   

10.
热膜式气体流量传感器在实际使用过程中,其芯片表面很容易被微小颗粒污染,使精度达不到工作要求.试验研究发现,传感器通电工作时,芯片表面电场力是造成污染物颗粒吸附堆积的主要因素.因此,污染物颗粒带电量的大小对芯片表面颗粒的堆积有着直接影响.文中采用Mastersizer 2000激光粒度分析仪和密立根油滴仪联合测量了颗粒群的平均粒径和平均带电量.激光粒度分析仪所测污染物颗粒的平均粒径为3.311 μm,根据此平均粒径值,密立根油滴仪所测3.2~3.4 μm范围内的颗粒所带平均带电量为6.4×10-17 C,此带电量即为整个颗粒群的平均带电量.  相似文献   

11.
基于动态光散射信号分形的颗粒测量技术研究   总被引:5,自引:0,他引:5  
申晋  郑刚  柏雪源  庄松林 《仪器仪表学报》2004,25(4):421-423,434
颗粒的动态光散射信号具有分形特征,通过对其特征值的分析,可以得到颗粒粒径信息。采用100nm、200nm、500nm和1000nm4种亚微米粒径范围的标准聚苯乙烯乳胶颗粒样品,分别求取了它们的动态光散射信号的分形维数。实验结果表明,颗粒粒径越小,对应的动态散射光分形维数越大;粒径越大,分形维数越小。从而证明了用分形维数表征颗粒粒径的可行性。与相关方法相比,分形方法具有所需的采样数据少、计算简便、适于实时测量等特点。  相似文献   

12.
The particle distribution of a dilute solid-liquid suspension through a stenosed arterial geometry was investigated. Particle image velocimetry (PIV) was used to determine the velocity as well as to acquire the flow images. The light intensity scattered by particles was evaluated to determine the particle distribution. Flow separation exists where the flow emerges from the stenosis throat. From the PIV images, the particle density distribution exhibited differing non-uniform characteristics which vary with flow rate, particle size and particle concentration. At low flow rates, a particle-free layer is formed. As the flow rate is increased, particles accumulate in concentric recirculation orbits within the downstream vortex. Particles with larger size and higher concentration tend to accumulate more towards the center of the vortex.  相似文献   

13.
Scattered light intensity distributions from microscratches on a silicon oxide wafer surface are simulated and analyzed for the purpose of microscratch sizing using a boundary element method (BEM)-based electromagnetic scattering simulator. At normal incidence, the characteristic scattered light resulting from microscratches appears in two symmetric regions of scattering angles, namely, at high and low angles. The scattered light intensities at high and low angles show characteristic fluctuation according to the depth and width variations of microscratches. It is found that the size of a microscratch can be obtained from the scattered light intensities at these characteristic angles. We propose microscratch sizing map which uses the detected light intensities to size the microscratches. Once the map is created, quick and easy categorization of microscratch size can be realized by collating the detected intensities with the map. The major advantage of using the map is the ability to measure simultaneously not only microscratch width but also depth. Generally, the depth cannot be obtained from an imaging system. Several experiments demonstrate the feasibility of our scheme and their results are in very good agreement with the simulation results.  相似文献   

14.
A novel probe head design is introduced, which enables in-line monitoring of particle sizes in undiluted stirred fluids using dynamic light scattering. The novel probe head separates a small sample volume of 0.65 ml from the bulk liquid by means of an impeller. In this sample volume, particle sizing is performed using a commercially available fiber-optical backscatter probe. While conventional light scattering measurements in stirred media fail due to the superposition of Brownian’ motion and forced convection, undistorted measurements are possible with the proposed probe head. One measurement takes approximately 30 s used for liquid exchange by rotation of the impeller and for collection of scattered light. The probe head is applied for in-line monitoring of the particle growth during microgel synthesis by precipitation polymerization in a one liter laboratory reactor. The in-line measurements are compared to off-line measurements and show a good agreement.  相似文献   

15.
This work concerns a method for measuring the local size distribution of spherical particles diffusing in a fluid. It is based on the light scattering theory and makes use of an ordinary Laser Doppler Anemometry apparatus. The required information is obtained by analyzing and processing the signal from the PM, which observes the measuring volume at the angle of 90. The pinhole is replaced by a slit oriented in such a way that the intensity of the scattered light depends only on the diameter of the particle and on a single space variable. A direct calibration of the response of the optical system is used to compute the size distribution from the scattered light probability density.  相似文献   

16.
通过实验和模拟研究磨粒对润滑油摩擦性能的影响。首先通过微纳米压/划痕试验测量含磨屑润滑油的摩擦因数。同时,建立边界润滑体系模型,采用分子动力学方法模拟含磨屑润滑油膜在不同载荷下沿膜厚方向的压缩率和密度分布;对体系的上下固体壁面施加方向相反的剪切速度,计算出壁面原子的应力、摩擦力、正压力和摩擦因数;分析不同粒径磨屑的动态行为特征;通过减少润滑油分子数量,探究乏油工况下含磨屑润滑体系的摩擦性能。结果表明,润滑体系摩擦因数的模拟值与试验值一致;磨屑的存在会降低油膜的压缩率,同时在高载下磨屑的存在会对油膜的分层产生破坏,影响磨屑附近的密度分布;含小粒径磨屑的润滑体系的摩擦因数比含大粒径磨屑的润滑体系的小,表明磨粒聚集长大现象会恶化润滑油的润滑性能;磨屑在剪切过程中同时存在滚动和滑动,含小粒径磨屑的润滑体系剪切过程中表现出波动幅度更大的角速度;随着载荷的增大,磨屑角速度减小,波动幅度降低;在乏油工况下,磨屑会在剪切过程中出现变形破碎现象。  相似文献   

17.
表面散射浊度测量研究   总被引:5,自引:0,他引:5  
本文在理论上计算了球形粒子对光的单次散射及多重散射解 ,证明了通过检测 90°方向散射光强度来获得样品浊度方案的优越性。随着样品浊度的增加 ,当考虑样品的多重光散射后 ,90°方向散射光强与浊度的线性度下降。设计了表面散射浊度在线测量系统 ,当 Formazin标准液在 0~ 1 0 0 0 NTU范围内时 ,获得了散射光强与浊度的线性度优于± 3% ,测量结果表明用表面散射法来测量浊度具有测量范围宽、线性好的优点。  相似文献   

18.
A novel method for detecting and sizing airborne particles at single particle level is presented in this paper. When a particle hits a metal electrode which is grounded, electrostatic charges will be transferred between the particle and the electrode. As a result, an electrical current pulse will be generated in the measurement system. The number of the signal pulse represents the number of particles in the sample. To determine the effect of the particle size on the magnitude of the signal, the correlation between the magnitude of the signal and the size of particle was experimentally investigated. The results show that the magnitude of the measured signal is linearly proportional to the square of particle’s diameter. Such a correlation can be used to evaluate particle size from the measured signal. The airborne particle detection method presented in this paper can be used for counting and sizing airborne particles at single particle level.  相似文献   

19.
Dai LL  Tarimala S  Wu CY  Guttula S  Wu J 《Scanning》2008,30(2):87-95
We have employed a laser scanning confocal microscope (LSCM) to study the structure and dynamics of microparticles at Pickering emulsion interfaces. The microparticles can have rich morphology at the emulsion interfaces, ranging from an aggregated structure to colloidal lattices, with a possibility of involving heterogeneous particles. With a specific interest in colloidal lattices, we find that although the enhanced electrostatic repulsion explains the formation of colloidal lattices by sulfate-treated polystyrene (S-PS) particles, it fails to interpret the unsuccessfulness of assembling lattices containing single-species carboxylate-treated polystyrene (C-PS) particles. A small percentage of C-PS particles in the colloidal mixture does not disturb the formation of lattices made of S-PS particles. The LSCM also provides a meaningful way to probe dynamic information. The diffusion of single particles at the emulsion interfaces depends strongly on the oil phase viscosity, particle size, and particle wettability. A highly curved emulsion interface slows the motion of microparticles at oil-water interfaces but the interface curvature effect decreases with increasing oil phase viscosity. Although the confocal microscope was originally used as an imaging tool, we find that the thermodynamic equilibrium of colloidal lattices can be disturbed and even destroyed when increasing the output laser intensity.  相似文献   

20.
Nanoparticle Tracking Analysis (NTA) has been applied to characterising soot agglomerates of particles and compared with Transmission Electron Microscoscopy (TEM). Soot nanoparticles were extracted from used oil drawn from the sump of a light duty automotive diesel engine. The samples were prepared for analysis by diluting with heptane. Individual tracking of soot agglomerates allows for size distribution analysis. The size of soot was compared with length measurements of projected two-dimensional TEM images of agglomerates. Both the techniques show that soot-in-oil exists as agglomerates with average size of 120 nm. NTA is able to measure particles in polydisperse solutions and reports the size and volume distribution of soot-in-oil aggregates; it has the advantages of being fast and relatively low cost if compared with TEM.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号