基于稀疏分解和背景差分融合方法的图像处理技术

针对传统融合算法处理聚焦区域能力弱、边缘效果差以及目标轮廓提取存在缺陷等问题,提出了基于稀疏分解和背景差分融合的方法.稀疏分解经过鲁棒主成分分析方式提取多聚焦图像轮廓,从而为源图像的准确分离奠定基础;背景差分融合依照源图像与增强图像的差异图提取轮廓信息以准确定位聚焦区域,从而防止引入人工干扰.结果表明,与传统方法相比,本文提出的方法在很大程度上提升了融合效果,能够很好地加强其对噪声的鲁棒性,同时表现出很好的视觉效果.     

Parameters of Exterior Ballistic Feature Points Extraction in Radar Measurement Data by EMD

The problem of measuring exterior ballistic feature points is always difficult to solve and it is essentiale on exterior ballistic measurement. By analysis of radar reflection characteristics and non-stationary echo signals of exterior ballistic feature points, the echo data of exterior ballistic feature points is measured by using the continuous wave radar. The parameters of feature points are extracted by the empirical mode decomposition method (EMD) of Hilbert-Huang transform (HHT) spectrum analysis technique. The radar echo signal model and EMD extraction model are established to analyze the exterior ballistic mutation point detection and EMD extraction method of aliasing echo signal. Typical feature point parameters of exterior ballistic in rocket flight tests are carried out and the effectiveness of the method is verified. A new method of measuring the parameters of exterior ballistic feature point is therefore presented.     

pFFT方法在波浪与结构作用中的不规则频率消除技术

对于求解波浪与大型结构物作用的pFFT方法,即预修正快速傅里叶变换方法(Pre-corrected Fast Fourier Transform),该文提出了消除"不规则频率"影响,从而保证在各频率下均可得到正确解的求解技术。该方法通过在内水面上配置源点的方法得到了唯一解的积分方程,并通过叠加物体内部积分方程而得到了便于求解的方形矩阵。算例表明:该方法能够消除"不规则频率"的影响,在整个频率内均可得到精确的计算结果;对于大型计算,在计算效率和内存空间的使用上,均较传统的高阶边界元方法有很大优势。     

煤层高压脉动水锤器的脉冲特性研究

从理论上确定了高压脉动水锤装置峰值压力的大小及脉动水力锤击波的传播速度,分析了主弹簧的性能参数,设计试验测定了高压缸的压力,结果表明,在0.0044s内,装置峰值压力由2.77MPa激增至14.0MPa;供水压力为4MPa时,能够产生17MPa脉冲波。此脉冲波以交变应力的形式作用于煤体,能够改变煤层孔隙网络的通透性。     

衍射光栅槽形隆起的数学建模及演变规律

以79g/mm的中阶梯衍射光栅为目标,研究衍射光栅机械刻划过程中铝膜的槽形隆起机制。首先,经过4次坐标变换,建立了光栅槽形的塑流剖面。然后,基于Lee and Shaffer提出的滑移线场模型,在塑流剖面内建立起包含滞留区域的滑移现场模型,并根据Dewhurst and Collins提出的矩阵算法对滑移线场进行求解,最终得到槽形隆起尺寸模型。最后,通过DEFORM软件对槽形隆起尺寸的演变规律进行模拟分析。     

矩孔夫琅禾费衍射的解析解和数值解

通过对衍射屏透光函数进行二维傅里叶变换和离散型快速傅里叶变换,分别得到矩孔夫琅禾费衍射的光强分布的解析表达式和数值结果。然后借助Matlab软件强大的作图功能实现了两种情况下光强分布的可视化仿真,具体分析了衍射图像随矩形孔径大小的变化情况。最后通过将数值解和解析解直接比较,指出提高数值解图像分辨率保证结果有效可靠的关键性因素是对输入信号进行适当的补零。     

Surface shape measurement of mirrors in the form of rotation figures by using point diffraction interferometer

The paper deals with the use of a point diffraction interferometer (PDI) to study the surface shape of rotation figures. The relations are given for the correspondence of the coordinates on the surfaces of an ellipsoid, a paraboloid and a hyperboloid as well as on an interferogram. Using PDI and Zygo white-light interferometer (WLI), we experimentally investigated the surface shape of the grazing incidence ellipsoid with the multilayer reflective coating on a wavelength of 0.154 nm with the following parameters: length is 55 mm, half-axis are 6 and 235 mm. The results coincided with an accuracy of 73 nm (RMS) without taking into account the PDI lateral resolution, and with an accuracy of 50 nm (RMS) with taking it into account, which ensures the local angles measurement accuracy of the ellipsoid-shaped reflecting surface at a level of 3 μrad. We think that this difference may be attributed to the limited lateral resolution of PDI and errors of frames stitching of WLI; nevertheless, we do believe that the PDI measurement accuracy is in the range of sub-μrad.     

简谐波在土木工程领域中的应用探析

对简谐运动进行了介绍,研究了简谐波在土木工程频域中的作用,指出用简谐波进行频域分析比用其他波形分析更具有优势,且根据简谐波推导出的某些计算方法在进行计算分析时有着效率高的优势。     

Study of Leaching of Multimetal Sulphides Through an Interdisciplinary Approach

The leaching of a real multimetal bulk concentrate cannot often be adequately understood on the basis of published literature on simpler and often ideal systems because the process is far too complex, Moreover, the data can become ambiguous in the absence of adequate information on raw materials. Thus any process development work requires a thorough knowledge of the raw material characteristics. This paper describes the use of an interdisciplinary study for a better understanding of ammonia leaching of multimetal sulphides. The techniques employed comprise of X-ray diffraction, thermal analysis, chemical analysis and microscopy.     

Evaluating surface deformation and near surface strain hardening resulting from shot peening a tempered martensitic steel and application to low cycle fatigue

The plastic deformation resulting from shot peening treatments applied to the ferritic heat resistant steel FV448 has been investigated. Two important effects have been quantified: surface roughness and strain hardening. 2D and 3D tactile and optical techniques for determining surface roughness amplitude parameters have been investigated; it was found that whilst R_a and S_a were consistent, S_z was generally higher than R_z due to the increased probability of finding the worst case surface feature. Three different methods for evaluating the plastic strain profile have been evaluated with a view to establishing the variation in yield strength near the surface of a shot peened component. Microhardness, X-ray diffraction (XRD) line broadening and electron backscatter diffraction (EBSD) local misorientation techniques were applied to both uniaxially deformed calibration samples of known plastic strain and samples shot peened at intensities varying from 4A to 18A to establish the variation in plastic strain and hence the variation in yield strength. The results from the three methods were compared; XRD and EBSD profiles were found to be the most similar with microhardness profiles extending much deeper into the sample. Changes in the measured plastic strain profile after exposure to low cycle fatigue and the correlation of these changes with the cyclic stress–strain behaviour of the material are also discussed with a view to assessing the importance of the dislocation profile in component life assessment procedures.