基于CCD的管内移动机器人管道缺陷检测系统

设计制作了一种独立轮驱动直进式管内移动机器人，适合于Ф131mm管径的金属管道，装载CCD图像采集系统获得管内壁图像，图像存储在PC机上采用数字图像处理技术进行后续处理，实现管内腐蚀、裂痕和涂层损坏等缺陷检测，并得到了很好的实验结果。     

卫星解码数字图像块效应计算机后处理方法

分块余弦变换(BDCT)已经被广泛应用于国际图像压缩标准并取得了良好的效果。然而,在有损图像处理中都存在着块效应问题。为了消除卫星数字图像块效应,这里结合卫星图像的特点,在文献^［4］的DCT后处理方法基础上进行改进,提出一种改进的解码图像块效应后处理方法。此方法不仅可以减少卫星图像块效应和提高图像质量,而且减少了DCT块效应后处理时间,提高了解码图像后处理效率。具有广泛的应用性。     

CT设备探测器损坏对图像重建质量的影响及解决方案

本文探讨了计算机X射线断层影像设备(CT)探测器上含有坏损探测元时的图像重建质量改善方案。对于发生损坏的探测元上的数据,利用其两侧正常工作的探测元上的数据进行插值估计,再使用基于滤波反投影的CT图像算法重建得到修正后的图像。分别模拟CT设备探测器上的探测元少量坏死和多量坏死的情况,对校正前和校正后的CT图像进行对比实验。未经过算法校正的CT图像含有明显的环形伪影,经过文中算法校正后的CT图像几乎无环形伪影存在,保留了图像细节信息。文章针对CT设备中探测器上探测元损坏作为问题点提出了行之有效的方案,校正后的图像质量满足需求,同时降低了CT设备高值元器件的更换成本。     

天文观测CCD相机中Smear效应的消除

为了有效消除帧转移型相机的Smear效应,针对其成像机理及特性,提出了一种基于背景估计的适用于序列图像中Smear效应的消除方法.该方法通过对含有Smear效应的原始图像灰度分布进行统计分析,自适应判定Smear效应的发生位置;然后,采用截尾均值滤波(ATMF)技术高精度估计Smear效应的强度;最后,通过差分的方式消...     

基于贝叶斯网络的芯片质量视觉检测

提出一种零件视觉检测方法,提取图像的暗点数、边缘点数和面积等图像特征,使用Netica软件构建具有10个属性节点和9个类节点的贝叶斯网络分类器,对各种缺陷和损坏零件进行识别,试验表明该方法具有较高的精度和效率。     

光学合成孔径复原图像的振铃探测与消除

针对相位平移误差使光学合成孔径图像的复原出现的振铃效应,提出了一种结合视觉感知的振铃探测与消除方法。首先,提出并利用梯度方向随机度和局部方差值两项指标计算得到图像纹理区;然后,根据不同阈值的Canny算子检测出全边缘与主边缘,并将主边缘邻域内的全边缘作为待筛选的边缘振铃;最后,结合人类视觉系统的纹理掩盖效应分别得到振铃区与平坦区。此外,在图像分区基础上,选择亮度相似度因子作为自适应参数,利用双边滤波进行图像处理。实验显示:处理后Lena图像的峰值信噪比提高了10.8%,分辨率板的结构相似度提高了0.057。结果表明:该方法能够对图像以像素精度分区,可以在保持边缘与纹理的同时,有效消除振铃效应,提高图像复原质量。     

受损门座式起重机臂架的结构分析

臂架是门座式起重机重要的承重结构。它在起吊时会受到大的轴力和弯矩作用而产生较大的应力。当臂架出现小的损坏，又因为工期无法停下修复时，需要重新对其强度进行校核计算才能安全使用。通过ANSYS Workbench建立了损坏臂架的有限元模型，计算了不同工况下上节臂、中间节臂和下节臂上的最大等效应力；着重考察了臂架损坏位置的等效应力值，得到了不同工况下臂架工作时的危险位置；研究了臂架的侧向刚度，对MQ4080门座机在中间节臂损坏三根腹杆件的情况下的结构进行了验证，验证发现降级使用能够保证结构的强度刚度满足要求。     

等面积递归分解的部分重叠局部直方图均衡

针对现有的直方图均衡算法在图像细节信息增强的同时无法保持输入图像亮度的缺点,以部分重叠局部直方图均衡算法（POSHE）为基础,将递归分解的思想引入子块图像直方图均衡过程,提出了一种改进的部分重叠局部直方图均衡算法。子块图像根据其累积概率密度（CDF）的中值递归地进行不同深度的分解,然后对每一个分解的子图像在其灰度范围内进行直方图均衡,并将均衡后的子图像合并,最后根据移动步长对子块图像进行线性或双线性插值消除块效应对图像细节信息的影响。实验结果表明,这种算法既能有效地增强图像的细节信息,又能保持输入图像的亮度,并且彻底地消除了块效应对图像均衡结果的影响,使均衡后的图像具有更加自然的视觉效果。     

CMOS图像传感器光子转移曲线辐照后的退化机理

针对EMVA 1288标准测试辐照后互补金属氧化物半导体(CMOS)图像传感器的重要性能参数(光子转移曲线和转换增益)适用范围受限的问题,提出了针对辐照后CMOS图像传感器光子转移曲线和转换增益的改进的测试方法。该方法通过调整测试条件,限制辐照后CMOS图像传感器的暗电流和暗电流非均匀性噪声,求解出辐照后正确的器件性能参数,从而直观地得知辐照所引起的器件性能变化。利用该方法进行了实验测试,结果显示:辐照导致转换增益比辐照前退化了7.82%。依据此结果分析了辐照导致光子转移曲线和转换增益退化的机理,认为转换增益的退化是由于质子辐射引起的电离效应和位移效应导致暗电流、暗电流非均匀性增大所致。本文为掌握CMOS图像传感器的空间辐射效应提供了理论基础。     

基于霍尔元件的润滑点无油检测系统

通过分析使用于钢坯剪断机的真空滴油式注油器的工作原理,分析了引起润滑点无油的主要原因在于注油器的损坏和油路管道的堵塞,并根据这两种情况,利用霍尔效应的原理,设计并制造了可检测摩擦运动副处是否有油的滑润点无油检测系统。该系统还具有声光报警功能、控制功能和一些其它的辅助功能。采用该系统可避免机床零件的损坏,保证机床安全可靠地运行。     

Electron beam-induced thickening of the protective oxide layer around Fe nanoparticles

There are many circumstances in science where the process of measuring the properties of a system alters the system. An imaging process can exert an inadvertent effect on the object being observed. Consequently, what we observe does not necessarily represent what had been present before the observation. Normally, this effect can be ignored if the consequence of such a change is believed not to be significant. The expansion of nanostructured materials has made high-resolution transmission electron microscopy one of the indispensable tools for probing the characteristics of nanomaterials. Modification of nanoparticles by the electron beam during their imaging has been widely noticed and this is generally believed to be due to electron beam-induced heating effect, defect formation in the particles, charging of the particle, or excitation of surrounding gases. However, an explicit experimental identification of which process dominates is often very hard to establish. We report the thickening of native oxide layer on iron nanoparticle under electron beam irradiation. Based on atomic level imaging, electron diffraction, and computer simulation, we have direct evidence that the protecting oxide layer formed on Fe nanoparticle at room temperature in air or oxygen continues to grow during an electron beam bombardment in the vacuum system typical of most TEM systems. Typically, the oxide layer increases from approximately 3 to approximately 6 nm following approximately 1h electron beam exposure typically with an electron flux of 7 x 10(5)nm(-2)s(-1) and an vacuum of approximately 3 x 10(-5)Pa. Partial illumination of a nanoparticle and observation of the shell thickening conclusively demonstrates that many of the mechanisms postulated to explain such processes are not occurring to a significant extent. The observed growth is not related to the electron beam-induced heating of the nanoparticle, or residual oxygen ionization, or establishment of an electrical field, rather it is related to electron beam-facilitated mass transport across the oxide layer (a defect-related process). The growth follows a parabolic growth law.     

A method of observing the area of contact and the mechanical breakdown of a surface film

A new method of observing the contact area was applied to the investigation of the effect of surface roughness on the mechanical breakdown of a surface film. This method uses the difference in secondary electron emission yields from the carbon surface film and from the base metal. Contact spots between the gold surfaces are visible as bright spots on the secondary electron image.

The contact resistance decreases with increasing surface roughness in the region of low surface roughness. However, the greater the tangential displacement and contact load, the less the surface roughness effect becomes. The results of contact resistance are supported by analyses of the area of film removal.     

On the calculation of magnetic fields generated by coils

The edge effect in electron microscopical images is proposed to be measured in length units by using a ratio of the edge or near-to-edge signal enhancement or depletion integrated over all this feature along a line-scan across an edge, to the mean signal away from the edge, giving the result in length units. This approach is applied to quantification of the edge effect in Auger electron images, which is examined by using specimens with sharp edge terminated overlayer terraces, both chemically homogeneous and heterogeneous. The following combinations of overlayer/substrate materials were used: Si/Si of three different overlayer thicknesses, W/W and W/Si, and line-scans across the edges were recorded in both the low- and the high-energy Auger electrons mode, i.e. Si LMM and Si KLL or W NOO and W MNN. The experimental results are presented for the 3-, 10- and 20-keV primary electron energies. Owing to a low signal-to-noise ratio in the measured data, basic relations between the effect appearance and the experimental conditions were revealed only: on both Si and W homogeneous specimens with a surface step, the edge enhancement is the dominating subphenomenon while at the W terrace edge on the Si substrate, the ‘penetration’ of the radiation characteristic to both areas separated by the step, to the neighbouring feature, is observed as the most significant effect. The quantification has shown that the effect is, first of all, proportional to the step height, amounting to one-third to up to the full height, while the material dependence was weak, equally to the dependence on the Auger electron energy. The primary electron energy dependence is increasing in accordance with expectation. The results indicate that the effect cannot be modelled simply by the interaction volume cut by the surface step but phenomena such as subsurface electron channelling along the sidewall have to be taken into account.     

Enhancement of the Breakdown Strength in Accelerators with Radio-Frequency Quadrupole Focusing

On the basis of experimental data on the effect of the electron loading in accelerators with radio-frequency quadrupole focusing and their analytical processing, a conclusion is drawn that the electrodes of the accelerating system are contaminated during the operation of an ion gun. Special measures, including the purification of the proton beam in the matching channel and cleaning of the electrodes of the accelerating system by RF conditioning, reduce the effect of the electron loading and enhance the breakdown strength of the accelerating structure up to 450 kV/cm.     

Natural color scanning electron microscopy based on the frequency characteristics of the human visual system

The principles of image formation in natural color scanning electron microscopy (NC-SEM) are discussed in detail. This method is based on the frequency characteristic of the human visual system. It is shown that the Mach effect and masking effect are important in the characteristics. The former, which can enhance structural details, is visually similar to the edge effect in secondary electron (SE) images, and the latter is required for proper representation of very degraded color information obtained from a light microscope. When using these effects suitably, an NC-SEM image with the resolution equivalent to that of an SEM image can be acquired, though it is composed of an SEM image and a special video microscopy (VM) image with a resolution much lower than the SEM image of the identical view. The NC-SEM is more effective than the SEM in observation. interpretation, and analysis of various samples with important color information.     

The statistics of the thermal motion of the atoms during imaging process in transmission electron microscopy and related techniques

The concern of this work is the influence of the thermal motion of the atoms on electron scattering simulations, used for quantitative interpretation of results in high-resolution electron microscopy. We distinguish between the influence of inelastic phonon excitation and the effect of a moving lattice on images generated by elastically scattered electrons. It is shown that, analog to aberrations, the impact of a moving lattice differs substantially with respect to different imaging conditions and cannot be described by the Debye–Waller damping applicable in XRD. We derive a new formalism, based on the frozen lattice and multislice approach, to incorporate the statistics of the thermal motion into elastic TEM imaging simulations, taking into account different imaging conditions. The averaging over different atom positions is generally performed within a density matrix framework, which can be linearized in the special case of off-axis electron holography. All findings are supported by explicit numerical simulations: molecular dynamics simulations are performed to get a realistic thermal motion and the electron scattering simulations are performed within the new multislice algorithm.     

Defining the radiation chemistry during liquid cell electron microscopy to enable visualization of nanomaterial growth and degradation dynamics

We present a critical review of methods for defining the chemical environment during liquid cell electron microscopy investigation of electron beam induced nanomaterial growth and degradation. We draw from the radiation chemistry and liquid cell electron microscopy literature to present solution chemistry and electron beam–based methods for selecting the radiolysis products formed and their relative amount during electron irradiation of liquid media in a transmission electron microscope. We outline various methods for establishing net oxidizing or net reducing reaction environments and propose solvents with minimal overall production of radicals under the electron beam. Exemplary liquid cell electron microscopy experiments in the fields of nanoparticle nucleation, growth, and degradation along with recommendations for best practices and experimental parameters are reported. We expect this review will provide researchers with a useful toolkit for designing general chemistry and materials science liquid cell electron microscopy experiments by ‘directing’ the effect of the electron beam to understand fundamental mechanisms of dynamic nanoscale processes as well as minimizing radiation damage to samples.     

A systematic investigation of the charging effect in scanning electron microscopy for metal nanostructures on insulating substrates

Scanning electron microscopy is perhaps the most important method for investigating and characterizing nanostructures. A well‐known challenge in scanning electron microscopy is the investigation of insulating materials. As insulating materials do not provide a path to ground they accumulate charge, evident as image drift and image distortions. In previous work, we have seen that sample charging in arrays of metal nanoparticles on glass substrates leads to a shrinkage effect, resulting in a measurement error in the nanoparticle dimension of up to 15% at 10 kV and a probe current of 80 ± 10 pA. In order to investigate this effect in detail, we have fabricated metal nanostructures on insulating borosilicate glass using electron beam lithography. Electron beam lithography allows us to tailor the design of our metal nanostructures and the area coverage. The measurements are carried out using two commonly available secondary electron detectors in scanning electron microscopes, namely, an InLens‐ and an Everhart–Thornley detector. We identify and discriminate several contributions to the effect by varying microscope settings, including the size of the aperture, the beam current, the working distance and the acceleration voltage. We image metal nanostructures of various sizes and geometries, investigating the influence of scan‐direction of the electron beam and secondary electron detector used for imaging. The relative measurement error, which we measure as high as 20% for some settings, is found to depend on the acceleration voltage and the type of secondary electron detector used for imaging. In particular, the Everhart–Thornley detectors lower sensitivity to SE₁ electrons increase the magnitude of the shrinkage of up to 10% relative to the InLens measurements. Finally, a method for estimating charge balance in insulating samples is presented.     

降低渗硼层本质脆性对其磨粒磨损特性的影响

利用MM-200型磨损试验机,研究了通过固体硼铬稀土共渗降低渗硼层本质脆性对其磨粒磨损特性的影响。并进行了应用试验,同时利用固体与分子经验电子理论对含铬Fe2B相的价电子结构进行了分析,结果表明,脆性的下降可使渗硼层的耐磨粒磨损性能提高0.27-0.80倍,而且实际应用效果显著,铬原子的溶入改变了Fe2B相的价电子结构,从而使渗硼层的本质脆性降低。     

Effect of the sample annealing temperature and sample crystallographic orientation on the charge kinetics of MgO single crystals subjected to keV electron irradiation

This paper focuses on the effect of sample annealing temperature and crystallographic orientation on the secondary electron yield of MgO during charging by a defocused electron beam irradiation. The experimental results show that there are two regimes during the charging process that are better identified by plotting the logarithm of the secondary electron emission yield, lnσ , as function of the total trapped charge in the material Q_T. The impact of the annealing temperature and crystallographic orientation on the evolution of lnσ is presented here. The slope of the asymptotic regime of the curve lnσ as function of Q_T, expressed in cm² per trapped charge, is probably linked to the elementary cross section of electron–hole recombination, σ_hole, which controls the trapping evolution in the reach of the stationary flow regime.