一种改进的特征匹配算法在碎片云测量建模中的应用

为满足超高速撞击典型Whipple防护构型的损伤评估需求,利用图像处理技术对碎片云序列阴影图像进行深入研究.使用超高速序列激光阴影成像仪得到三组不同实验条件下碎片云发展过程的高清阴影图像,分别对每组最具代表性的2帧进行图像处理分析;根据碎片云图像特点以及碎片运动特性,提出了一种改进的碎片二次特征匹配算法,该方法包含碎片...     

Evaluation of water distribution in a small operating fuel cell using neutron color image intensifier

Neutron radiography is one of the useful tools for visualizing water behavior in operating fuel cells. In order to observe the detailed information about the water distribution in membrane electrode assembly (MEA) and gas diffusion layer (GDL) in fuel cells, a high performance neutron imaging system is required. A neutron color image intensifier (NCII) is a high spatial resolution and high sensitivity neutron image detector. We have developed an imaging system using an NCII for visualizing the behavior of water in fuel cells. The pixel size of the imaging system is around 4.7 μm in the small view field. By using this system, water distribution of a small sized fuel cell was observed continuously every 20 s at the Thermal Neutron Radiography Facility (TNRF). In the results, the water area appears from the GDL and MEA regions, and expanded to the cathode side channel with time. However, the voltage was gradually reduced with time, and steeply dropped. It is considered that the reduction and the drop of voltage were caused by a blockage of gas flow due to accumulation of water in the GDL and the gas flow channel in the cathode side.     

Lossless color medical image compression using adaptive block‐based encoding for human computed tomographic images

The advancement in medical imaging systems such as computed tomography (CT), magnetic resonance imaging (MRI), positron emitted tomography (PET), and computed radiography (CR) produces huge amount of volumetric images about various anatomical structure of human body. There exists a need for lossless compression of these images for storage and communication purposes. The major issue in medical image is the sequence of operations to be performed for compression and decompression should not degrade the original quality of the image, it should be compressed loss lessly. In this article, we proposed a lossless method of volumetric medical image compression and decompression using adaptive block‐based encoding technique. The algorithm is tested for different sets of CT color images using Matlab. The Digital Imaging and Communications in Medicine (DICOM) images are compressed using the proposed algorithm and stored as DICOM formatted images. The inverse process of adaptive block‐based algorithm is used to reconstruct the original image information loss lessly from the compressed DICOM files. We present the simulation results for large set of human color CT images to produce a comparative analysis of the proposed methodology with block‐based compression, and JPEG2000 lossless image compression technique. This article finally proves the proposed methodology gives better compression ratio than block‐based coding and computationally better than JPEG 2000 coding. © 2013 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 23, 227–234, 2013     

面向直线类目标图像测量的对焦算法

针对直线类边缘图像测量中的对焦问题,文章提出了一种利用被测边缘梯度信息的对焦算法。在包含被测边缘的区域内,该算法计算各行或列中被测边缘点的梯度值,求出这些梯度值的平均值;根据聚焦时边缘梯度相对达到最大的成像特点,将所求得的边缘梯度平均值作为聚焦程度的评价准则。该算法与两种常用对焦算法——灰度差分法和灰度方差法的对比试验表明,在保持平滑性不变的情况下,该算法的单峰幅值比灰度方差法大10倍;它克服了灰度差分法依赖阈值的缺点,而且平滑性明显优于后者,其局部波动平均幅值仅为灰度差分法的1/10。     

Improvement of the digital image correlation close to the borders of an object

The measurement error of the finite-element-based Digital Image Correlation is reduced along the borders of an object by using the precise measurement, obtained by Virtual Image Correlation (VIC). The proposed method is called Virtual and Digital Image Correlation (VDIC). The boundary, identified by the VIC with a subpixel precision, is used firstly to create an adapted mesh and secondly to create a pixel mask. Futhermore, the VDIC also uses the VIC measurement of the boundary in the deformed state as a constraint on the radial displacement field along the border. The optimal values of the parameters of the VDIC are discussed throughout a sensitivity analysis. The compared performances of the constrained and unconstrained VDIC are obtained thanks to a synthetic test of a plate with a hole in tension. Finally, the method is checked on a sample geometry which includes holes and a U-shaped notch.     

Impact of wear debris on striated muscle‐ a comparative in‐vivo study with titanium and stainless steel

Wear debris and corrosion products of metal implants induce biological events that may have severe consequences for skeletal muscle microcirculation. We therefore studied in vivo leukocyte‐endothelial cell interaction and leukocyte transmigration in skeletal muscle after confrontation with characterised titanium and stainless steel fretting corrosion particles, and compared these results with those of the bulk materials. Using the hamster dorsal skinfold chamber preparation and intravital microscopy, we could demonstrate in 30 animals that stainless steel induces a more pronounced inflammatory answer in contrast to the implant material titanium. However we were not able to show a general benefit of bulk vs. debris. Overall the study suggests that not only the bulk properties of orthopaedic implants but also the microcirculatory implications of inevitable wear debris may play a role in determining biocompatibility and ultimately longlivety of an implant. The skinfold chamber is a feasible and versatile model for observation of the dynamic process of microvascular response after foreign‐body implantation, and offers much perspective. With a minimum of adverse host reaction, our results indicate that titanium still represents the gold standard in metallic implant material, even in the case of generated wear debris, which shows a comparatively low inflammatory potential.     

基于数字图像的空间目标滚转角测量方法

本文分析了几种摄影状态下空间目标滚转角的测量问题,提出了一种从单站光测数字图像确定目标滚转角的螺旋线法。该方法通过在圆柱形目标表面涂上边界为螺旋线的四区域标志,综合运用直方图均衡化、Susan边缘检测以及Hough变换等数字图像处理技术,从光测图像中得到各个时刻目标中轴线与螺旋线的相交线段的长度,由此可高精度测出空间目标的滚转角,从而有效地解决了靶场试验中空间目标滚转角的测量难题。仿真与实践结果表明,该算法可操作性强,精度较高。     

模糊推理在边缘检测中的应用

针对传统边缘检测算法边缘轮廓模糊、易产生伪边缘等缺点,提出一种基于模糊逻辑推理策略的边缘检测新方法,在无需确定阈值的情况下对数字图像进行边缘提取。给出一种以变化的3×3模板为基准的模糊推理规则,通过对周围像素点的垂直和水平方向以及连续四点像素的黑白分布的判断,提取出图像中的黑点、白点和边缘部分。实验结果表明:与Robert算法相比,该方法对图像中噪声和双重边缘的抑制以及对曲线的圆度轮廓的提取都有很好的效果。     

一种模糊红外目标边缘和不变特征提取方法

针对红外图像中模糊目标难以分割和识别的情况,提出以小波多尺度滤波分解后的逼近图像作为自适应域值进行图像二值化的方法,由此分割出模糊图像中的目标,提取目标的轮廓边缘.然后,提出一种新的矩计算方法提取目标的不变性特征.实验结果表明,该方法具有很强的抗噪和抗扰性能,能有效提取复杂背景中模糊目标的平移、缩放和旋转不变量,极大提高了运动模糊目标识别的可靠性.     

Feature extraction through generalization of histogram refinement technique for local region‐based object attributes

Content based image retrieval (CBIR) is used to retrieve digital images from large databases. However, the problem of retrieving images on the basis of the contents remains largely unsolved. The proposed method of image retrieval is based on the information provided by histogram analysis of the intensity or grayscale values of images. Some additional properties are also calculated and used that are based on regional characteristics of various objects in the image. The need to retrieve the additional regional properties arises due to the fact that the standard histograms are insensitive to small changes in images. Many images of different types can have similar histograms, because, histograms provide only a coarse characterization of an image. This is the main disadvantage of using histograms. This research is based on the concept of Histogram Refinement (Pass and Zabih, IEEE Workshop Appl Comput Vision ( 1996 ), 96–102). Distributing the grayscale image intensities by splitting the pixels using their intensity values into several classes just like the histogram refinement method can provide an estimate of the object characteristics present in an image. After the calculation of clusters using a color refinement method, the inherent features of each of the clusters is calculated based on the regional properties of the clusters. These additional region based features expound some structural information of the image. Finally, all of these features are used for image retrieval. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 298–306, 2011;     

Theoretical and experimental study of the wear factor for a diamond stone-cutting tool

Results are provided for a study of the wear factor in cutting Kursebi deposit teshchenite with a diamond cutter segmented wheel 1250 mm in diameter made of SAM 500/400 diamonds. Analysis shows that diamond consumption varies within considerable limits. For wheels with a diameter of 500–1250 mm, the maximum consumption reaches 0.9–1.5 carat/m². Translated from Izmeritel’naya Tekhnika, No. 3. pp. 45–47, March, 2009.     

水石流冲击信号能量分布试验研究

泥石流冲击谱是泥石流固液两相介质运动特性的综合表征,探索泥石流冲击信号的能量大小及其分布特性是合理确定泥石流冲击荷载的关键环节。运用自行研制的试验模型,实施了15种试验工况的泥石流冲击试验,获取了85 000多个测试数据。依据固相比为0.16、粒径组为0.8～1.5 cm水石流冲击测试结果,运用db8小波基变换对试验结果进行8层小波分解,得到频率范围分别为0～0.195Hz,0.195～0.391 Hz,0.391～0.781 Hz,0.781～1.562 5 Hz,1.563～3.125 Hz,3.125～6.25 Hz,6.25～12.5 Hz,12.5～25 Hz和25～50 Hz共九个频率段的冲击信号,据此揭示了不同频段冲击信号能量分布规律。从低频段至中高频段水石流冲击能量非线性衰减,90%以上的冲击能量分布在小于0.195 Hz的低频部分;水石流在中高频段的冲击能量总体呈衰减分布,但在频段三和频段六出现较显著峰值,表明水石流也存在一定阵流现象;水石流中固相粒径越小,低频段至高频段的冲击能量衰减速度越慢。研究成果可为进一步实施泥石流冲击荷载精细实验研究提供一定科学依据。     

Digital image correlation for strain measurement in plastic film blowing process

Surface deformation study of a polymer film during plastic film blowing (PFB) extrusion process though is considered essential, is difficult to execute as the process is fast and continuous. Digital image correlation (DIC) is an optical technique that is non-destructive, highly accurate and designed to measure deformations from micro to macro scale. DIC can be proposed as a reliable tool to understand the relationship of polymer structure-processing-properties. In this literature, digital image correlation, its basic principle of operation and reliability guided DIC for continuous large deformation are comprehensively explored. Versatility of DIC, and the conditions that affect the measurement algorithm as well as preceding use of DIC in polymer processes are reviewed. The implementation and potential use of DIC in PFB are described.

This review was submitted as part of the 2019 Materials Literature Review Prize of the Institute of Materials, Minerals and Mining run by the Editorial Board of MST. Sponsorship of the prize by TWI Ltd is gratefully acknowledged.     

液体样品预处理装置中黏稠液体定量转移结构创新

为解决液体样品预处理装置中罐体之间黏稠液体定量转移无法准确实现的问题,综合应用发明问题解决理论(TRIZ)和约束理论(TOC)进行问题分析与求解。从系统的角度分析了样品预处理装置的组成及要素间的相互关系,基于TRIZ进化模式和TOC必备树确定了样品预处理装置的核心问题,应用基于TRIZ的计算机辅助创新软件InventionTool 3.0中的冲突模块、标准解模块和效应模块进行了设计方案的选择、评价和修正,提出了实现液体样品预处理装置中黏稠液体定量转移的原理解。     

铝基碳化硅精密铣削刀具磨损实验研究

针对铝基碳化硅切削加工中刀具易磨损、寿命低、切削难度大和加工成本高等问题,选用不同材料的硬质合金铣刀及金刚石铣刀进行切削加工实验,并利用扫描电镜和工具显微镜对高体积分数铝基碳化硅铣削时刀具磨损形态进行了分析研究.研究表明:硬质合金刀具前刀面和刃口磨损主要形式为粘结磨损和微崩刃,后刀面磨损主要为刻划磨损,而金刚石铣刀加工时刀具磨损很小;YG6X铣刀材料微观组织致密,抗磨损能力较强,宜粗加工时选用;金刚石刀体的硬度远大于SiC颗粒,且金刚石与工件的摩擦系数小,金刚石铣刀寿命远大于硬质合金铣刀,宜精加工时选用.     

高动态范围图像融合过程中的噪声抑制算法

高动态范围成像通常需要利用多个不同曝光时间的低动态范围图像来合成高动态范围图像。在合成后图像噪声会进一步放大,可能导致最终的高动态范围图像视觉质量严重降低。针对合成图像需要保留低曝光图像中高亮区域的细节信息以及高曝光图像中低暗区域的细节信息,且图像噪声与亮度有关这一问题,本文提出一种基于亮度分区、噪声水平估计的高动态范围图像融合过程中的噪声抑制算法。首先,根据图像的亮度信息,确定低动态范围图像的不同亮度区域;然后对图像不同亮度区域,利用重叠块估计噪声水平,根据得到的噪声水平,指导图像的稀疏去噪;最后,对处理后的低动态范围图像,采用融合方法合成高动态范围图像。实验结果表明,所提出的算法能有效地抑制图像噪声,合成的高动态范围图像具有更好的视觉质量。     

简述数字暗房的构建

数字暗房由输入部分、影像处理部分、色彩管理部分、输出部分和数据存储部分组成。本文对各部分的功能和基本装备分别详予阐述。     

A simple optical method for the differentiation of two types of polymeric wear debris in tissue samples

A simple low-cost optical method for differentiating two birefringent plastic materials in tissue sections is described. The method relies on the measurement of the refractive indices of the materials as standard samples, then mounting the specimen containing the mixture of materials in a medium of intermediate refractive index. The optical properties of the materials in this mounting medium permit their separate identification by use of Becke's lines. In the specific example used, ultra-high molecular weight polyethylene (UHMWPE; refractive indices 1.521 and 1.529) and polyacetal (refractive indices 1.476 and 1.492) were distinguishable from each other by mounting in sandalwood oil (refractive index 1.510). Illustrative results are given for the analysis of the comparative amounts of these two polymers in the tissues adjacent to five knee replacements obtained at revision surgery. In every case there were more UHMWPE particles than polyacetal particles.     

On the analysis of notched concrete beams: From measurement with digital image correlation to identification with boundary element method of a cohesive model

A way of coupling digital image correlation (to measure displacement fields) and boundary element method (to compute displacements and tractions along a crack surface) is presented herein. It allows for the identification of Young’s modulus and fracture parameters associated with a cohesive model. This procedure is illustrated to analyze the latter for an ordinary concrete in a three-point bend test on a notched beam. In view of measurement uncertainties, the results are deemed trustworthy thanks to the fact that numerous measurement points are accessible and used as entries to the identification procedure.     

Asymptotic modeling of the long-period oscillations of tribological parameters in the wear process of metals under heavy duty sliding conditions with application to structural health monitoring

Different aspects of the long-period oscillations of tribological parameters in the wear process of metals under constant heavy duty sliding conditions are theoretically investigated on the basis of the previously constructed mathematical model. The obtained asymptotic formula for the period of oscillations agrees with the quantitative predictions known in the literature. The period of oscillations is suggested as a diagnostic parameter in assessing the health of operating tribosystem. An approximate formula for the phase of oscillations of relaxation type in the Lotka-Volterra nonlinear mathematical model is derived by the relaxation oscillation method.