再现图像细节抑制散斑噪声技术研究

为了消除数字全息再现像产生的散斑噪声,一种基于边缘检测各向异性扩散方程的去噪算法被提出。在各向异性扩散方程(PM)基础上,通过将边缘检测算子结合梯度算子引导扩散过程,边缘检测算子对噪声具有低敏感度,可以更好地区分边缘信息,达到数字全息再现像去噪目的。通过去噪效果图对比和与中值滤波、均值滤波、小波变换滤波算法峰值信噪比(PNSR)的比较,表明本文提出的算法具有更好的去噪效果,在去除噪声的同时有效保护了图像的细节信息。     

KT-D型银盐全息干版曝光特性的研究

本文首先对用KT-D型银盐全息干版记录的全息图的曝光特性进行了实验研究,获得了全息图的衍射效率与曝光能量的关系曲线。然后应用Kogelnik的耦合波理论测算出乳胶折射率及其调制度的曝光特性,对其折射率调制机理作出必要的理论分析,并获得了KT-D型全息干版的性能参数。     

大数值孔径光学镜约束多级衍射机理

针对基于激光照明的离轴全息显微成像系统存在散斑和寄生条纹噪声,以及基于部分相干光照明的离轴数字全息显微技术存在相干条纹对比度差的问题,本文提出了一种基于单色LED照明的衍射相位显微成像系统。该系统利用大数值孔径物镜及光栅对物光进行多级衍射,并采用4f系统和空间滤波器分离出0级和+1级信息,分别作为参考光和物光,最终两束光在CCD阵面上干涉产生离轴全息图,从而形成共光路全息成像结构。通过理论分析和计算,对实验用到的光学元器件进行选型,确保衍射光频谱信息能够分开且满足抽样条件。最后与传统激光离轴数字全息显微成像检测结果进行对比,实验结果表明,本文提出的系统能够获得较高的成像准确度和信噪比。     

应用含硫氰酸铵的稀释显影液提高全息图的衍射效率

本文研究了用含有硫氰酸铵的稀释显影液处理的全息图的特性。利用电子显微镜和分光光度计测量的结果表明,与稀释显影全息图片相比,用含有硫氰酸的稀释显影液处理的全息片中的银颗粒的尺寸变小,其透过率增大。较小的银颗粒引起的光散射也将减小。基于测量结果并利用有效介质理论和耦合波理论可以解释利用含有硫酸铵的稀释显影液能够增加全息图的衍射效率。     

全色光致聚合物的全息记录 特性及应用研究

优选亚甲基蓝、曙红Y、吖啶橙分别作为红敏、绿敏、蓝敏光敏剂,制作出全色光致聚合物全息记录材料.全息记录特性测量表明,该材料在红、绿、蓝三基色激光记录下均具有大于90%的衍射效率和较高的感光灵敏度(70 mJ/cm²).开展了该材料的角度复用、波长复用全息存储实验,在材料的同一位置处分别以不同参物光夹角及不同记录波长成功存储了多幅全息图,且再现图像清晰明亮,相互之间无明显串扰,表明该材料具有良好的全息记录性能及应用价值.     

基于阶调映射的高动态范围图像纸媒再现研究

高动态范围（high dynamic range,HDR）图像由于亮度范围大,细节层次丰富,比普通图像能更好地记录和展现真实场景的明暗细节,已广泛应用于医疗图像、航空遥感、虚拟现实、跨媒体出版等领域中。但是其动态范围较现有显示媒介有较大差异,在获取、显示及输出上,无法直接再现于低动态范围媒介,特别是纸媒介,这给HDR图像的常规应用特别是印刷再现带来了巨大挑战。 本研究从色适应角度提出用于数字印刷的HDR图像再现思路,首先测试了不同纸媒的基本光学属性,即白度、不透明度、色度等参数。结合印刷品网目阶调,通过回归法对纸媒的光学属性与印刷阶调、色彩再现之间的关系进行了数理统计分析,获得纸媒光学属性与印刷品网点密度和色度之间的关系（Paper Medium Properties to Printed Dot Density and Colorimetric Coordinates,PMP-PDDC）;根据测试结果建立了纸媒动态范围与HDR图像的动态范围的对应关系,并依据此关系建立了多级阶调映射模型（Multi-Level Tone Mapping Model, MTMM）,提出了一种亮度可控和细节补偿修正的多级阶调映射技术。结合HDR图像与纸媒介的动态范围特性,确定基础层压缩系数和细节层补偿系数的阈值,对HDR图像进行映射处理,保持不同阶调分区内原有场景等关键特征的视觉感知;最后,根据PMP-PDDC和MTMM,采用CANON IPF8300数字喷墨印刷机实现HDR图像的数字印刷再现,采用标准HDR图像进行输出测试,主要运用主客观评价的方法进行印刷再现质量评价。 实验表明,采用纸媒属性白度为107.60%,不透明度为97.58%的时候,纸张再现图像具有更好的阶调范围、细致的层次表现、更大的色域和更逼真的色彩效果。根据MTMM采用3级阶调映射和3个不同的细节参数处理HDR图像,能够获得更精确的映射结果,保持更多的图像细节。 本文依据纸媒介属性所提出的方法具有较好的印刷再现感知结果,保持了更多的细节信息,建立多级阶调映射算法模型。实验结果也表明了亮度可控和细节补偿修正的多级阶调映射技术的有效性,并实现了数字印刷纸媒最佳的再现效果。论文结果对HDR图像的跨媒体再现具有重要的理论指导意义,有助于解决数字印刷媒介难以再现HDR图像细节信息的难题,为HDR图像的跨媒体传播奠定了理论和技术基础。     

基于傅里叶成像网络的全息粒子成像技术研究

数字全息图重建可以获得物体的三维信息,在医疗、环保、化工等需要测量颗粒大小和三维信息的相关研究有着重要的科学意义和使用价值。粒子全息定位通常有计算复杂和重建精度不足等问题,为了解决相关问题,我们采用一种基于傅里叶成像网络的方法,利用傅里叶变换的特性,能够有效提取全息图的频率特征,结合深度学习技术,通过可学习的滤波器和全局感受野处理输入数据的空间频率,实现对全息图快速和准确的处理,不仅提高了数据处理效率,还具备了更强大的特征提取能力,从而实现对粒子的精确定位。本文通过实验和仿真两方面验证,并与Dense＿U＿net网络对比。结果显示,基于傅里叶成像网络的方法在定位精度和速度上都有显著的提升。并通过实验验证了该方法可行性。     

一种基于块模糊增强的玉米田遥感图像边缘检测方法

针对高分一号卫星(GF-1)玉米田遥感图像中玉米田光谱复杂和地块边缘模糊导致的面积统计误差大的问题,本文提出一种块模糊增强和最小值边缘提取相结合的边缘检测方法进行玉米田地块分割处理,以减小面积统计误差。首先将彩色遥感图像从RGB变换到I¹I²I³彩色空间,提取出含丰富特征的单色图I¹;然后利用模糊理论对I¹进行基于块的增强处理;再对增强后的图像进行最小值边缘提取;最后利用Full Lambda-Schedule算法对区域边缘进行优化。通过与Canny和Sobel等边缘提取方法比较,证明本文的边缘检测结果能有效地分割出玉米田地块目标,减少了玉米田光谱复杂和边缘模糊带来的影响,检测出的边缘更符合玉米田实际分布,玉米田面积统计结果更符合实际。     

数字全息显微在医学影像中的发展与最新应用

随着CCD等光电成像器件和计算机技术的迅猛发展,数字全息显微技术不断发展成熟起来,以其非接触、定量、三维成像等特点广泛应用于医学影像领域。本文综述了数字全息显微技术在生物医学方面的发展;比较了数字全息显微技术与其它显微技术在生物医学成像方面的优缺点;分析总结了不同全息显微影像信息系统;论述了不同光源结构对数字全息显微成像效果的重要影响以及相应算法补偿;列举了数字全息显微在生物医学中的最新应用。     

像前与像后预放大与数字全息显微成像比较

随着数字全息显微技术在医学影像信息处理领域的广泛应用,本文对其影像信息系统进行了研究。基于菲涅耳衍射公式和线性系统理论,对像前及像后预放大数字全息显微成像过程进行了理论分析,推导了系统的点扩散函数,分析了系统成像的横向分辨率,并对这两种系统的成像性能进行了比较,最后利用分辨率测试板进行了实验验证。     

Recent progress in axisymmetric drop shape analysis (ADSA)

Axisymmetric Drop Shape Analysis (ADSA) is a powerful technique for the measurement of interfacial properties from the shape of drops/bubbles. It relies on the best fit between theoretical curves with known surface tension values and an experimental profile. Despite the general success of ADSA, inconsistent results are obtained for nearly spherical drop shapes. Since the source of this and possible other limitations are unknown, the entire ADSA technique including hardware and software is systematically scrutinized. The hardware consists of electronics, and optical and mechanical components that generate a digital image of a drop. Since the quality of images has a considerable impact on the surface tension measurements, general guidelines for the use of hardware components are developed to enhance the quality of the image. The scrutiny of the software of ADSA is significantly more involved. The software consists of image analysis and numerical schemes. One of the key elements is the modularization of the software, since a generic software package is not suitable for all experimental situations. As a result, a more versatile image analysis module is introduced. In this context a variety of state-of-the-art edge detection techniques are studied, and a more robust technique is adopted. The two existing ADSA numerical schemes are also compared systematically, and the more efficient one is implemented. It is shown that even this superior numerical scheme has convergence problems for nearly spherical drops. This difficulty is due to numerical truncation and accumulation of round-off errors, which are the ultimate limitation of all numerical schemes. This intrinsic limitation becomes more pronounced as drops become closer to spherical in shape, but there were no objective criteria available to define "close to spherical drops". Therefore, a quantitative criterion called shape parameter is introduced to identify the range of applicability of ADSA. The improved version of ADSA not only determines the interfacial properties more accurately but, through the shape parameter, also provides an a priori knowledge of the accuracy of the results.     

计算机辅助一清片径向展开薄层色谱定性与定量方法初探

径向薄层色谱法（RTLC）是一种将样品呈圆形或环状点样,然后将展开剂从中心向外沿径向输送的薄层色谱方法。在一定的展开距离内,RTLC是一种分离快速、扩散小、不拖尾的高效分离和半制备方法。目前关于RTLC分离的报道较多,但对RTLC定性和定量的报道较少。该文采用自编程方式结合图像处理软件,实现RTLC图像数字化处理,形成RTLC数字化图谱,并对RTLC进行定性与定量方法学验证,建立了一清片RTLC定性与定量方法。辅助计算机技术,对一清片径向展开薄层色谱定性与定量方法进行初探。结果表明,该方法用于RTLC定性的可靠度较好,但用于RTLC的定量,仍有不足之处,这可能与实验环境条件等有关。通过搭载更好的分离和数据采集设备,RTLC会有适合的用武之地。计算机图像处理和自编程方法的结合给了RTLC和其他一些分析相关的技术广阔的发展前景。相信未来在计算机技术的辅助下,薄层色谱技术会迈上一个新的台阶。     

Improvement of interfacial tension measurement using a captive bubble in conjunction with axisymmetric drop shape analysis (ADSA)

Axisymmetric drop shape analysis (ADSA) is a method to measure surface tension using drop or bubble profiles. Combining ADSA with a captive bubble configuration (ADSA-CB) facilitates pulmonary surfactant related studies. The accuracy of ADSA-CB is crucially dependent on the quality of the bubble profile extracted from the raw image. In the previous version of ADSA-CB, a global thresholding method was used to segment the bubble profile. However, that technique is of limited accuracy for images with noise and/or lack of contrast. In this paper, a new generation of ADSA-CB using the Canny edge detector was developed. To obtain better results, a novel edge smoothing technique, termed axisymmetric liquid fluid interfaces-smoothing (ALFI-S), was introduced and incorporated with the Canny edge detector to extract bubble profiles. The performance of the new version of ADSA-CB was evaluated using captive bubble images under different conditions. The results suggest that the new methodology is capable of producing accurate surface tension values under a variety of circumstances.     

Experimental approach for microscale mechanical characterization of polymeric structured materials obtained by additive manufacturing

In this paper, an original experimental method is developed for local strain characterization at the surface of additively manufactured polymeric materials. The process used herein is material extrusion. This experimental method is based on the use of microscopic speckle pattern deposited at the surface of micro single edge notched specimen (μ_SENT) made of acrylonitrile butadiene styrene (ABS). Two configurations of filament orientation were used for the specimen manufacturing. Images of the μ_SENT specimen surface were recorded during in-situ tensile test. The quantitative analysis of images was made by digital image correlation (DIC). The evolutions of the local strain heterogeneities and the crack tip are evidenced on the kinematic fields. It is shown that the crack propagates in the low resistance path which is the interface area between filaments. It is also evidenced that the intersection of perpendicular filaments in two adjacent layers blocks crack growth. The local strain evolutions at the surface of the specimen are compared to the macroscopic response of the material. The method developed herein allows the determination of the materials mechanical properties. The identification of the crack tip location using digital image correlation (DIC) and J-integral calculation lead to plot the J-R curve. The J-R curves comparison of the two specimen configurations shows that the fracture toughness is directly related to the material structure.     

Influencing parameters on measurement accuracy in dynamic mechanical analysis of thermoplastic polymers and their composites

Long-term predictions of material properties such as stiffness and creep resistance are important in many engineering applications and require high reliability and accuracy. This is especially true for polymer materials and their composites as their viscoelastic nature results in time-dependent material behaviour and any measurement uncertainties or errors amplify in long-term predictions. To measure this behaviour at smallest loadings, Dynamic Mechanical Analysis (DMA) is frequently declared as an ideal method. However, the measurement accuracy and repeatability of this method is strongly influenced by (i) the testing fixture and corresponding loading mode, (ii) the sample preparation and (iii) the plotting scale to interpret the test results. In this study, relevant experimental parameters were found for DMA and a proper procedure was designed, which was then applied to measure the viscoelastic behaviour of a highly temperature and creep resistant thermoplastic polymer (polyethersulfone) and of a highly graphite filled polypropylene composite. In combination with finite element simulations and in-situ strain measurements by digital image correlation (DIC), the main influences on measurement accuracy of three-point-bending DMA were identified and subsequently used to determine measurement guidelines. Using these guidelines, DMA measurements allow quantitative determination of the viscoelastic response for rigid polymer and composite materials.     

Spline wavelet analysis for voltammetric signals

Application of wavelet multifrequency channel decomposition (WMCD) in electroanalytical chemistry is presented in this paper. A new approach on this digital processing technique, to extract useful information from high noise signals in voltammetry, is described in detail. The method of constructing a model of B-spline WMCD and its application with 2nd, 3rd and 4th order B-spline in the linear scan voltammetry are thoroughly discussed and several results obtained. If the suitable optimal wavelet basis and frequency scale value are selected, the absolute values of the peak relative errors are less than 2% when the signal-to-noise ratio (S/N) is greater than 0.2, and the absolute values of the peak potential relative errors are less than 12% when S/N is greater than 0.3. The processed results of experimental data with high noise are also satisfactory. The whole computation is simple and needs shorter time than other signal processing methods.     

我院医用数字X射线摄影系统设备质量控制及机房放射防护现状分析

为分析我院医用数字X射线摄影系统(DR)设备质量控制状态及机房放射防护现状,本研究选取截止2019年6月我院安装完毕并已验收检测合格投入使用的5台DR设备作为研究对象,依据WS 521-2017《医用数字X射线摄影(DR)系统质量控制检测规范》的检测要求和技术指标,对DR设备质量控制状态进行评价,根据GBZ 130-2013《医用X射线诊断放射防护要求》的检测要求和技术指标对机房放射防护情况进行评价。质量控制检测结果显示,5台DR设备中有2台DR设备各有1项检测项目不符合国家标准要求,总合格率为60.0%。各项检测指标中,管电压指示的偏离、光野与照射野四边的偏离不合格各有1台,合格率为80.0%;有用线束半值层、输出量重复性、有用线束垂直度偏离、光野与照射野中心、输出量线性、曝光时间指示的偏离合格率均为100.0%。机房放射防护检测结果显示,5台DR设备机房58个检测点的周围剂量当量率检测中有6个检测点发生泄露,泄露发生率为10.3%。结果表明,我院DR设备质量控制检测不合格率较高,DR机房泄漏风险也较高,需加强DR设备的质量控制,完善机房辐射安全管理,以保证影像辅助诊断的质量,以及放射工作人员和公众在放射诊疗过程中免受一切不必要的电离辐射。     

A strategy to improve the accuracy of digital simulation for electroanalytical chemistry

A strategy for digital simulation methods was presented for solving partial differential equations, called as IPBFP which is to insert M points before the first time point of the usual way, to decrease simulation errors. The theoretical analysis and simulation results show that it can improve the fully implicit method with any dimensionless diffusion coefficient A, Crank-Nicolson method with large and Saul'yev method with small . The IPBFP is convenient to arrange the simulation time points flexibly and reduce calculation time and errors. This approach can combine the merits of non-uniform time grid and uniform time grid methods in simulation for electrochemical studies.     

A High‐Throughput Method for Determining the Stability of Pigment Dispersions

Summary: An approach for the high‐throughput preparation and characterisation of aqueous pigment dispersions is described and evaluated. The use of ultrasonication as a rapid technique for dispersing pigments using polymeric dispersants was developed. The results are comparable to those obtained using time‐intensive conventional high‐energy ball mill processing. The quality of the pigment dispersion was evaluated in a high‐throughput fashion using digital image analysis and the results correlated with particle sizes, determined by photo‐correlation spectroscopy.

Cuvettes containing dispersions of varying particle size.