手机数码比色法测定土壤中总磷含量

基于在酸性介质中,磷酸二氢钾(KH2PO4)与钼酸钠及抗坏血酸作用,生成蓝色的络合物,溶液的颜色随着KH2PO4浓度的增加而逐渐变浅,并呈现一定颜色梯度的原理,提出了使用手机数码比色法测定土壤中总磷含量的分析新方法。方法的相对标准偏差(RSD)为1.2%,对样品进行加标回收实验,加标回收率在102%¹03%。方法方便快捷,成本低,适合现场分析,是一种农民自行测定土壤中总磷含量的新方法。     

Deep Learning and Entropy-Based Texture Features for Color Image Classification

In the domain of computer vision, entropy—defined as a measure of irregularity—has been proposed as an effective method for analyzing the texture of images. Several studies have shown that, with specific parameter tuning, entropy-based approaches achieve high accuracy in terms of classification results for texture images, when associated with machine learning classifiers. However, few entropy measures have been extended to studying color images. Moreover, the literature is missing comparative analyses of entropy-based and modern deep learning-based classification methods for RGB color images. In order to address this matter, we first propose a new entropy-based measure for RGB images based on a multivariate approach. This multivariate approach is a bi-dimensional extension of the methods that have been successfully applied to multivariate signals (unidimensional data). Then, we compare the classification results of this new approach with those obtained from several deep learning methods. The entropy-based method for RGB image classification that we propose leads to promising results. In future studies, the measure could be extended to study other color spaces as well.     

Simultaneous two-axis shearographic interferometer using multiple wavelengths and a color camera

Multi-component measurements in shearography and other applications of Electronic Speckle Pattern Interferometry (ESPI) are typically achieved using multiple optical configurations that are activated sequentially to measure each desired quantity separately. A novel optical setup is introduced here where orthogonal shearography measurements are simultaneously made using a single color-camera imaging multiple monochromatic light sources of different wavelengths. The Red–Green–Blue (RGB) sensors of a conventional Bayer type camera are read separately, thereby providing three independent color signals and independent ESPI phase maps. Orthogonal axis shearography is achieved using a modified shearography interferometer where a dichroic filter is added to provide a second wavelength-dependent measurement. The availability of the two surface slopes gives the opportunity for the data to be summed numerically to give the surface displacement shape. This application is of significant practical interest because the surface displacement measurement can be made under field conditions by taking advantage of the well-known optical stability of shearography measurements. The two simultaneously measured surface slopes also offer the possibility to mathematically compensate for non-uniformity and non-orthogonality in the image shear caused by mirror non-flatness and/or mirror misalignments.     

计算机辅助光弹性应力分析

本文提出一种新的计算机辅助光弹性应力分析方法,它具有全电子记录、全自动应力场分析、光路简单等优点。相位技术的采用使数据精度大大提高。文中给出了几种实验光路以及提高图象质量的方法,用对经受压圆盘光弹实验证明了方法的可行性。     

动光弹性法中若干问题的近期研究进展

为适应解决工程中越来越多动态力学问题的需求,在近年来计算技术、高速摄影技术、图像处理技术等迅速发展的基础上,本文对动光弹性法中的若干关键问题近期的研究进展作简要叙述。内容包括：(1)新型数字式动光弹仪的研制,这种光弹仪以激光光源取代多火花放电式光源,实现了连续、实时的强光源,以高速摄影系统取代原来多个相机的拍摄系统,利用计算机软件对整个系统装置进行控制,实现了图像的优化采集,为数字化处理图像提供了有力的保障;(2)静、动光弹性材料的探索,重点介绍了动光弹模型材料的新配方和新工艺;该工艺采用硅橡胶模具,无需使用脱模剂,利用常温固化形成环氧树脂板材或块体,可精密浇注,一次到位,材料具有良好的光力学性能;(3)动光弹的工程应用,利用新型数字式动光弹仪器以及环氧树脂浇注新的工艺进行了实际工程的研究,取得了一些有价值的结果。文中以某舰船中的部件舵机和基座及海岸工程中港口关键部位柱、柱帽连接部位为实例进行了动应力分析,证明了新研制的仪器和新材料均满足试验要求,有广阔的发展前景。     

动光弹性法中若干问题的近期研究进展

为适应解决工程中越来越多动态力学问题的需求,在近年来计算技术、高速摄影技术、图像处理技术等迅速发展的基础上,本文对动光弹性法中的若干关键问题近期的研究进展作简要叙述。内容包括:(1)新型数字式动光弹仪的研制,这种光弹仪以激光光源取代多火花放电式光源,实现了连续、实时的强光源,以高速摄影系统取代原来多个相机的拍摄系统,利用计算机软件对整个系统装置进行控制,实现了图像的优化采集,为数字化处理图像提供了有力的保障;(2)静、动光弹性材料的探索,重点介绍了动光弹模型材料的新配方和新工艺;该工艺采用硅橡胶模具,无需使用脱模剂,利用常温固化形成环氧树脂板材或块体,可精密浇注,一次到位,材料具有良好的光力学性能;(3)动光弹的工程应用,利用新型数字式动光弹仪器以及环氧树脂浇注新的工艺进行了实际工程的研究,取得了一些有价值的结果。文中以某舰船中的部件舵机和基座及海岸工程中港口关键部位柱、柱帽连接部位为实例进行了动应力分析,证明了新研制的仪器和新材料均满足试验要求,有广阔的发展前景。     

一种求解平面接触应力问题的光弹性—数值组合方法

本文提出一种求解平面接触应力最大值的光弹性—数值计算组合方法,仅从光弹性等差线上采集实验数据,然后用牛顿—拉斐逊技术与最小二乘法相结合计算出结果。文中推导了控制方程,阐述了方法,研究了实验数据取值区域、取值个数以及接触长度测试误差等因素的影响。用两类平面接触问题作为应用实例,结果符合工程要求的精度。     

五腿混凝土平台的三维光弹性应力分析

本文叙述了三维光弹性在五腿混凝土平台中的应用。为了简化和完成这个试验,采用了模拟四分之一的平台结构的光弹性模型,它承受着与原型相应的各种荷载,并且仔细地处理了它的边界约束条件。实验分析采用冻结法,最后确定了一些重要截面内外边界上的轴向和环向应力,并且得到了腿柱和罐体连接部位的应力集中。     

变弹模成层岩基受预锚荷载作用的三维光弹性实验研究

本文介绍了变弹模成层岩基受预锚荷载作用的三维光弹性实验过程。求出了岩基在锚固应力作用下锚根附近的应力场,并和电测成果、理论计算成果进行了比较,结果非常相近.为进一步探讨这些问题提供了可靠的依据.     

Jeffrey fluid flow due to curved stretching surface with Cattaneo-Christov heat flux

The two-dimensional (2D) motion of the Jeffrey fluid by the curved stretching sheet coiled in a circle is investigated. The non-Fourier heat flux model is used for the heat transfer analysis. Feasible similarity variables are used to transform the highly nonlinear ordinary equations to partial differential equations (PDEs). The homotopy technique is used for the convergence of the velocity and temperature equations. The effects of the involved parameters on the physical properties of the fluid are described graphically. The results show that the curvature parameter is an increasing function of velocity and temperature, and the temperature is a decreasing function of the thermal relaxation time. Besides, the Deborah number has a reverse effect on the pressure and surface drag force.