Low shear rheological behaviour of two-phase mesophase pitch

The low shear rate rheology of two phase mesophase pitches derived from coal tar pitch has been investigated. Particulate quinoline insolubles (QI) stabilised the mesophase spheres against coalescence. Viscosity measurements over the range 10–10⁶ Pa s were made at appropriate temperature ranges. Increasing shear thinning behaviour was evident with increasing mesophase content. At low mesophase contents the dominant effect on the near Newtonian viscosity was temperature but at higher contents it was the shear rate; temperature dependence declined to near zero. The data indicated that agglomeration could be occurring at intermediate mesophase volume fractions, 0.2–0.3. The Krieger–Dougherty function and its emulsion analogue indicated that in this region the mesophase pitch emulsions actually behaved like ‘hard’ sphere systems and the effective volume fraction was estimated as a function of shear rate illustrating the change in extent of agglomeration. At the higher volume fractions approaching the maximum packing fraction, which could only be measured at higher temperatures, the shear thinning behaviour changed in character and it is considered that this is possibly due to shear induced deformation and breakup of dispersed drops in the shear field.     

A Student's t-based density peaks clustering with superpixel segmentation (tDPCSS) method for image color clustering

Image color clustering is a basic technique in image processing and computer vision, which is often applied in image segmentation, color transfer, contrast enhancement, object detection, skin color capture, and so forth. Various clustering algorithms have been employed for image color clustering in recent years. However, most of the algorithms require a large amount of memory or a predetermined number of clusters. In addition, some of the existing algorithms are sensitive to the parameter configurations. In order to tackle the above problems, we propose an image color clustering method named Student's t-based density peaks clustering with superpixel segmentation (tDPCSS), which can automatically obtain clustering results, without requiring a large amount of memory, and is not dependent on the parameters of the algorithm or the number of clusters. In tDPCSS, superpixels are obtained based on automatic and constrained simple non-iterative clustering, to automatically decrease the image data volume. A Student's t kernel function and a cluster center selection method are adopted to eliminate the dependence of the density peak clustering on parameters and the number of clusters, respectively. The experiments undertaken in this study confirmed that the proposed approach outperforms k-means, fuzzy c-means, mean-shift clustering, and density peak clustering with superpixel segmentation in the accuracy of the cluster centers and the validity of the clustering results.     

显示器色彩管理规范化的研究

针对同一色彩在不同显示器之间呈现出的差异,根据显示器色彩管理的基本原理和规范化应用流程,通过实验测量对显示器及显示器色彩管理文件进行了校正和规范,并对显示器特性文件进行质量评价,结果表明应用色彩管理在数字化流程中会使显示器获得更好的显示效果。     

A robust video zero-watermarking based on deep convolutional neural network and self-organizing map in polar complex exponential transform domain

In this paper, a robust video zero-watermarking scheme for copyright protection using a combination of convolutional neural network (CNN) and self-organizing map (SOM) in polar complex exponential transform (PCET) space is presented. The scheme is developed not only to remedy the existing problems of lacking in some performance assessments but also to enhance the robustness. It starts with extracting the content feature of each frame by CNN and then some significant frames are selected using SOM clustering and maximum entropy. Secondly, the PCET is applied to all selected frames to abstract invariant moments, and further, is scrambled by a chaotic logistic map and is reduced in dimensions by singular value decomposition (SVD). Next, a binary sequence is generated by comparing adjacent values of the obtained compact PCET moments in the previous step, and further is permuted to produce a binary matrix. Finally, a bitwise exclusive-OR operation is imposed on the binary matrix and the encrypted watermark by the chaotic map to generate a zero-watermark signal. Experimental results demonstrate that the proposed scheme has adequate equalization and distinguishability of zero-watermarks as well as strong robustness against common signal processing, geometric, compression, and inter-frame attacks. Also, compared with existing video zero-watermarking and traditional video watermarking methods, the proposed scheme exhibits superior robustness.

     

一种直接高效的自然场景汉字逼近定位方法

为了提高经典目标检测算法对自然场景文本定位的准确性,以及克服传统字符检测模型由于笔画间存在非连通性引起的汉字错误分割问题,提出了一种直接高效的自然场景汉字逼近定位方法。采用经典的EAST算法对场景图像中的文字进行检测。对初检的文字框进行调整使其更紧凑和更完整地包含文字,主要由提取各连通笔画成分、汉字分割和文字形状逼近三部分组成。矫正文字区域和识别文字内容。实验结果表明,提出的算法在保持平均帧率为3.1 帧/s的同时,对ICDAR2015、ICDAR2017-MLT和MSRA-TD500三个多方向数据集上文本定位任务中的F-score分别达到83.5%、72.8%和81.1%;消融实验验证了算法中各模块的有效性。在ICDAR2015数据集上的检测和识别综合评估任务中的性能也验证了该方法相比一些最新方法取得了更好的性能。     

Facile preparation of homogenous waterborne poly(urethane/acrylate) composites and the correlation between microstructure and improved properties

Homogenous waterborne polyurethane/polyacrylate emulsions were synthesized based on the prepared polyurethane and polyacrylate through a facile process. The attention was attracted to the miscibility and performance of waterborne polyurethane and polyacrylate. The structures and properties of waterborne polyurethane and waterborne polyurethane/polyacrylate samples were characterized by using Fourier transform infrared spectroscopy, transmission electron microscope, X-ray photoelectron spectroscopy, X-ray diffractometer, thermogravimetric, and so forth, as well as solid content and tensile testing. The results showed that the micro morphology of waterborne polyurethane/polyacrylate emulsion presented single-phase structure with the stoichiometric polyacrylate content increasing from 33% to 80% to waterborne polyurethane. The waterborne polyurethane/polyacrylate films surface is rich in polyacrylate phase. Meanwhile, waterborne polyurethane/polyacrylate composites showed significant improvement in thermal stability and elongation at break, smaller particle size and narrower particle size distribution comparing with waterborne polyurethane.     

基于通道注意力机制的文本生成图像方法

针对文本生成图像任务中生成图像细节缺失及低分辨率阶段生成图像存在结构性错误的问题,基于动态注意力机制生成对抗网络（DMGAN）,引入内容感知上采样模块和通道注意力卷积模块,提出一种新的文本生成图像方法ECAGAN。在低分辨率图像生成阶段的特征图上采样过程中采用基于内容感知的上采样方法,通过输入特征图计算得到重组卷积核,使用重组卷积核和特征图进行卷积操作,确保上采样后的特征图和文本条件的语义一致性,使生成的低分辨率图像更加准确,利用通道注意力卷积模块学习特征图各个特征通道的重要程度,突出重要的特征通道,抑制无效信息,使生成图像的细节更丰富。此外在训练过程中结合条件增强和感知损失函数辅助训练,增强训练过程的鲁棒性,提高生成图像质量。在CUB-200-2011数据集上的实验结果表明,ECAGAN模型初始分数达到了4.83,R值达到了75.62,与DMGAN方法相比,分别提高了1.6%和4.6%,并且可改善生成图像结构错乱的问题,同时能够生成清晰的图像细节,语义一致性更高,更加接近真实图像。     

Mechanical properties of coated paper: Influence of coating properties and pigment Blends

The effect of percentage solids content, coating film thickness and plastic pigment on mechanical properties of coated paper was studied. The results showed that the tensile strength, TEA, stretch and tensile stiffness were improved as the percentage solids content and the coating film thickness were increased. Bending stiffness slightly increased when solids content was increased and showed higher values on increasing the coating film thickness. The addition of plastic pigment to both clay based and GCC based coating mixtures improved the mechanical properties considered in this study. Although tensile strength and tensile stiffness increased with the addition of plastic pigment of smaller particle size, stretch and TEA showed a reverse trend.