一种基于图像处理技术的柴油机单颗粒微观结构的分析方法

为了准确地定量分析柴油机单颗粒微观结构,采用Gabor滤波法、局部阀值法、改进的OPTA法等图像处理技术对微粒微观形貌图像进行特征提取,获得了微粒微观结构特征参数微晶尺寸、层面间距、曲率的计算统计方法.试验结果表明,该方法可以快速、准确地获取微粒微观结构特征参数,偏差率仅为0.15%,是研究柴油机微粒微观结构的重要工具.试验结果还表明,随着柴油机负荷的增加,微晶尺寸平均值从2.161 nm增加到2.180nm,而层面间距平均值和曲率平均值则分别从0.362 nm和1.228减小到0.360 nm和1.224.     

Comparative study on soot characteristics of non-swirling and swirling inverse diffusion iso-octane flames with biofuel 2,5-dimethylfuran addition

Due to the heavy consumption of the fossil fuels in the transportation sector and the furnace factory, a large amount of soot is discharged and seriously threatened the environment and the human health. The present work focuses on examining the characteristics of soot produced from iso-octane/2,5-dimethylfuran (DMF) non-swirling and swirling inverse diffusion flames (IDFs). Morphology, nanostructure, graphitization and oxidation reactivity of nascent soot particles from 100% iso-octane, 50% iso-octane/50% DMF and 100% DMF IDFs were investigated by using high resolution transmission electron microscopy, X-ray diffraction, and thermogravimetric analysis, respectively. The effect of swirling on the soot characteristics was discussed. Results demonstrate that the nascent soot from pure iso-octane flames shows the morphology with liquid-like deposition and turbostratic nanostructure, while the soot from pure DMF displayed more primary particle with the nanostructure contained by many well-organized lattice fringes. Because the mixability of air and fuel under the action of swirling is higher than that of non-swirling condition, the soot particles from swirling conditions reveal more ordered nanostructure with longer fringe length and lower fringe tortuosity, as well as higher soot graphitization and lower oxidation reactivity.     

金属型GPF对GDI发动机颗粒物微观特性的影响

采用高分辨透射电镜(HRTEM)对安装了金属型汽油机颗粒捕集器(GPF)的汽油缸内直喷(GDI)发动机颗粒物进行观察,研究了转速为1500 r/min,负荷分别为25％、50％、75％和100％工况下的GPF前、后端颗粒物微观形貌及微观结构参数变化.结果表明:组成颗粒物的基本粒子均呈近似球形,堆积形成链状、枝状和环状等...     

EGR对生物柴油颗粒物氧化活性及微观结构的影响

为研究废气再循环(EGR)及燃用调合生物柴油(B0,B20)对柴油机排放颗粒物(PM)氧化活性与微观结构的影响,通过一台4缸共轨柴油机进行试验,并采集燃烧颗粒物,使用热重分析仪(TGA)、高倍透射电镜(HRTEM)和拉曼光谱(RS)对颗粒物进行研究.结果表明:燃用同种燃料时,随着EGR率增加,颗粒中干碳烟含量增加,起始...     

Nanostructure and reactivity of soot from biofuel 2,5-dimethylfuran pyrolysis with CO2 additions

This paper investigated the nanostructure and oxidation reactivity of soot generated from biofuel 2,5-dimethylfuran pyrolysis with different CO₂ additions and different temperatures in a quartz tube flow reactor. The morphology and nanostructure of soot samples were characterized by a low and a high resolution transmission electron spectroscopy (TEM and HRTEM) and an X-ray diffraction (XRD). The oxidation reactivity of these samples was explored by a thermogravimetric analyzer (TGA). Different soot samples were collected in the tail of the tube. With the increase of temperature, the soot showed a smaller mean particle diameter, a longer fringe length, and a lower fringe tortuosity, as well as a higher degree of graphization. However, the variation of soot nanostructures resulting from different CO₂ additions was not linear. Compared with 0%, 50%, and 100% CO₂ additions at one fixed temperature, the soot collected from the 10% CO₂ addition has the highest degree of graphization and crystallization. At three temperatures of 1173 K, 1223 K, and 1273 K, the mean values of fringe length distribution displayed a ranking of 10% CO₂>100% CO₂>50% CO₂ while the mean particle diameters showed the same order. Furthermore, the oxidation reactivity of different soot samples decreased in the ranking of 50% CO₂ addition>100% CO₂ addition>10% CO₂ addition, which was equal to the ranking of mean values of fringe tortuosity distribution. The result further confirmed the close relationship between soot nanostructure and oxidation reactivity.     

三维瞬变喷雾场浓度与温度分布的激光干涉层析（2）──干涉图的图象处理

本文建立了一套对利用激光层析干涉术所拍得的干涉图进行图象处理的计算机图象处理系统，讨论了干涉图图系处理的有关理论，提出了用于干涉图的去噪、增强以及干涉条纹的提取与追踪细化的Ｋ—最近邻加权平均法、直方图均衡化、动态阈值分割、三点拟合法追踪细化等一整套方法，并对干涉图进行了实际处理。     

Formation and nanoscale-characteristics of soot from pyrolysis of ethylene blended with ethanol/dimethyl ether

Ethanol and dimethyl ether (DME) have been considered to be two of the most potential additives for conventional hydrocarbon fuels. This paper focused on the nanoscale characteristics of soot from ethylene pyrolysis with ethanol and DME additions. The pyrolysis experiments were conducted in a α-alumina tube flow reactor at 1273 K, 1373 K and 1473 K, with the replacement of 0%, 50% and 100% (mole fraction) ethylene by the two oxygenated fuels. The gas-phase kinetic modeling was also performed to explore and understand the soot formation process. The main pathways and some key soot precursors in the pyrolysis have been obtained. Soot samples were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) to acquire their internal structure and oxidation reactivity. Results showed that the mass of collected soot diminished with the increase of the replacement of ethylene by ethanol/DME. The effects of DME to inhibit the formation of soot were more obvious. The least amount of soot was collected in the pyrolysis of pure DME. Peak mole fraction of C₂H₂, C₄H₂, C₄H₄ and C₅H₅ also decreased with the increase of replacement of ethylene by ethanol/DME, displaying the same tendency with the variation trend of soot mass in the different pyrolysis conditions. According to TEM and HRTEM results, the additions of ethanol and DME could decrease the growth rate of soot contrasted with the pyrolysis of pure ethylene. Soot collected from the pyrolysis of pure DME at 1273 K and 1373 K showed a typical amorphous structure with short, highly-curved and turbulent fringe. With the reduction of the replacement of ethylene by DME, mature soot with longer and more ordered fringe formed at 1373 K and 1473 K. The sequence of the mean fringe tortuosity of soot samples was 100% ethylene<50% DME<100% ethanol<50% ethanol< 100% DME. The order was the same as the sequence of oxidation reactivity. Furthermore, with the increase of temperature, the mass of soot increased. More mature soot with higher degree of graphization, longer fringe length, smaller fringe tortuosity and lower oxidation reactivity was obtained. High correlation between soot nanostructure and soot oxidation reactivity was found.     

Evolution of the nanostructure, fractal dimension and size of in-cylinder soot during diesel combustion process

The nanostructure, fractal dimension and size of in-cylinder soot during diesel combustion process have been investigated for a heavy-duty direct injection diesel engine, using a total cylinder sampling system followed by high-resolution transmission electron microscopy and Raman scattering spectrometry. Different structural organizations of in-cylinder soot are found depending upon the combustion phase. It is revealed that both the fringe tortuosity and separation distance decrease as combustion proceeds, while the mean fringe length increases distinctly from 1.00 to 2.13 nm, indicating the soot evolution toward a more graphitic structure during the combustion process. The fractal dimensions of aggregates are in a range of 1.20–1.74 at various crank angles under the applied engine operating conditions. As temperature and pressure increase, the fractal dimension decreases significantly to a minimum at the early diffusion combustion stage. The soot particles become more compact again as the fractal dimension increases during the subsequent combustion period. Primary particle sizes start small, go through a maximum in the early diffusion combustion phase and decline again as combustion proceeds.     

热老化温度对碳烟氧化活性的影响

由于炽热尾气长时间冲击,柴油机微粒捕集器(DPF)中的沉积碳烟颗粒会发生热老化.本文通过改变惰性气氛下的温度,研究热老化对柴油机碳烟颗粒微观物理化学特性和氧化活性的作用规律.结果表明,随热老化温度的升高,氧化反应特征温度和表观活化能表征的碳烟颗粒氧化活性逐渐降低;氧化活性的降低来源于碳烟颗粒物理化学特性的改变,即微晶尺寸增大,微晶曲率和层间距减小,以A_D1/A_G值表征的石墨化程度提高,而以I_C—H/I_C=C峰高比表征的脂肪族C—H表面官能团相对含量降低.此外,柴油机碳烟颗粒微观结构、表面C—H官能团相对含量与碳烟氧化活性具有良好的相关性,其中微晶曲率对氧化活性影响最大.     

3D phase-differentiated GDL microstructure generation with binder and PTFE distributions

In this work, a new framework and model for the digital generation and characterization of the microstructure of gas diffusion layer (GDL) materials with localized binder and polytetrafluoroethylene (PTFE) distributions were developed using 3D morphological imaging processing. This new generation technique closely mimics manufacturing processes and produces complete phase-differentiated (void, fiber, binder, and PTFE) digital 3D microstructures in a cost- and time-effective manner for the first time. The results for the digital generation of Toray TGP-H-060 with 5 and 0 wt.% PTFE were in close agreement with confocal laser scanning microscope (CLSM) images as well as 3D X-ray tomography studies. The resulting structure can be readily used for analyzing transport processes utilizing commercial CFD software.     

基于图像处理技术的输电线路走廊烟火识别研究

识别输电线路走廊烟火对保障输电线路安全运行有重要意义。采用图像处理技术,在分析输电走廊环境下烟火特征的基础上,首先对监控视频图像数据进行采样、灰度化、滤波和图像增强等预处理,然后选择混合高斯法构建图像背景模型,并确定前景目标图像区域,最后将前景图像和烟火做特征比较,以排除干扰物影响并得到烟火目标。仿真分析空旷野外和居民村落两种环境,验证了该方法识别烟火的有效程度。     

Visual flame monitoring system based on two-color method

Monitoring and control of combustion flames in utility boilers are required in order to optimize combustion conditions. This paper presents an instrumentation system for the concurrent measurement of the temperature distribution and soot concentration of flames developed on the two-color principle. This system consists of an endoscope, an optical assembly with optical filters, a CCD camera, a frame grabber and associated image processing software. Experiments are performed on a methane-air combustor and the temperature fields and the soot concentrations corresponding to the flame images are obtained. The results have demonstrated that the system is capable of performing on-line measurement of flame and temperature distribution, providing temporal and spatial characterization of the combustion process. In addition, the combination of advanced optical sensing and digital image processing technique can help to define the threshold by the analysis of the background noise. Furthermore, the utilization of the filter technique can enhance the image presentation effect to an extent.     

基于图像处理的光伏局部阴影区域分割方法

为解决真实场景中光伏组件局部阴影区域分割受环境干扰的问题,该文提出基于图像处理的光伏局部阴影区域分割方法。根据光伏组件特征用改进的阈值分割方法提取组件边框,采用Hough变换检测组件边框线段,计算包围边框线段端点的最小凸包作为感兴趣区域。在感兴趣区域内再次使用改进的阈值分割方法提取局部阴影区域。用模拟仿真图像和真实场景图像验证该文所提方法的有效性,实验结果表明：所提方法可准确分割出光伏组件上的局部阴影区域且保持了遮挡区域的细节信息。与多阈值分割方法和基于Canny边缘检测的分割方法相比,该文所提方法的错误分类误差更小,类别像素准确率更高。     

ESPI testing of Arcton containers

The paper reports on the application of TV holography, more commonly known as electronic speckle pattern interferometry (ESPI), in the testing of Arcton bottles. A large number of Arcton bottles that have been returned to the factory for refilling exhibit dents of all sizes which occurred while in usage in the industrial environment.

A system comprising a pulsed ruby laser, a high resolution CCD camera and a computer with frame grabbing capabilities has been prototyped to test two bottles at a time. The testing consists of providing an initial no-load image which is captured by the speckle camera. A second image of the bottles under-load (small depressurisation), is subtracted from the first, giving good quality interference fringes. The resulting image clearly denotes regions of higher density fringe pattern centred around dents or irregularities of the cylindrical surface of the bottles. The operator homes in with a cursor to measure the fringe density which is compared with the allowable one and acceptance or rejection of the bottle is indicated on the pc's monitor. The whole operation takes place in less than 5 min and is controllable from the pc's keyboard.     

光伏阵列故障检测中的无人机红外图像拼接

红外遥感图像可用来检测光伏组件的异常发热,为获得大视野的地面信息需要图像拼接技术,该文提出一种基于快速鲁棒特征检测(speeded-up robust features,SURF)算子的红外光伏图像自动拼接算法。基于K-d树(Kdimension tree)算法的匹配结果,结合匹配对的坐标信息提出一种优化算法,减少了随机抽样一致(random sample consensus,RANSAC)算法的迭代次数,并采用最佳缝合线算法进行图像融合;然后优化平移变换模型、修正旋转序列的角度,基于待拼接图像和模板之间的重叠区域自动修正拼接参数。实现从图像序列到全景图的全自动拼接流程。试验表明,该方法使RANSAC算法的迭代次数平均减少93.26%,处理时间平均减少86.21%。在没有无人机位置和飞行方向的少参数条件下,基本消除了光伏组件的几何相似性导致的误匹配和累计误差。     

基于分数维的面向对象的图像分割

针对图像分割为图像处理与分析中的关键步骤,提出了一种基于分数维的面向对象的图像分割方法,用分数维特征量描述地物的纹理特征,利用地物的分数维值和光谱特征进行对象分割,在一定程度上降低了图像分割对光谱特征的依赖性.试验结果证明,该方法较准确,分割结果较连续,避免了按象元分割产生的散布式结果,适应于对几何信息和结构信息丰富的高分辨率图像进行后续分类.     

基于数字图像处理的LPG喷雾特性试验研究

使用高速纹影摄影和数字图像处理方法研究了具有相同喷孔直径的两个分别带有和不带双孔分流套的单喷孔喷嘴在MPI喷射条件下液态LPG燃料的自由喷雾过程,测量了喷雾贯穿距离、投影喷雾面积、喷雾体积和喷雾锥角等喷雾特性。通过与手工测量结果对比证明了数字图像处理方法测量结果的有效性。试验结果表明:喷射压力越高,喷雾贯穿距离、投影喷雾面积和喷雾体积越大,而喷雾锥角越小;带有双孔分流套的喷嘴雾化效果好,更有利于形成均匀混合气;在喷雾中期和后期,不带双孔分流套的喷嘴的喷雾贯穿距离长,但在喷雾初期的一段时间内,却比带有双孔分流套的喷嘴的喷雾贯穿距离短。     

Effects of NH3/H2/N2 addition on soot morphology and nanostructure in laminar co-flow ethylene diffusion flame

The present study investigated the effects of NH₃/H₂/N₂ addition on soot morphology and nanostructure in laminar co-flow diffusion flame of ethylene, by adopting the method of thermophoretic sampling combined with transmission electron microscope (TEM). The volume fraction of NH₃ varies from 10% to 30%, and the volume fraction of H₂ and N₂ are all 30%. The soot morphology evolution images were analyzed with the parameters representing size and fractal characteristics determined. Among the three diluents, the addition of NH₃ is found to have the best suppressing effect with the smallest primary particle size and least accumulated aggregates, especially at the lower flame heights. Meanwhile, H₂ addition is observed to advance the soot formation process due to the higher flame temperature. The soot particle images with a magnification time of 600,000 obtained from high-resolution transmission electron microscope (HRTEM) were processed by the processing code. The parameters describing the soot nanostructure were measured and analyzed with the fitted curves. It is found that the fringes of particles sampled from NH₃ enriched flames tend to be shorter and more curved, and the inter fringe spacing tends to be larger, indicating the nanostructure is more disordered and the particles are easier to be oxidized. Compared with the flames with NH₃ addition, particles from H₂ enriched flames show a more ordered and compact nanostructure. Finally, simulations were performed to further interpret the effects. Calculated results show that the NH₃ and H₂ addition obviously suppress the production of larger PAHs, and NH₃ is more effective than H₂, but this difference gradually narrows for greater PAHs. Simulations also indicate that the peak value of precursors in NH₃ enriched flame is delayed.