Non-coherent noise reduction in digital holography based on root mean square technique

In this paper, the root mean square (rms) technique is applied in order to reduce the non-coherent noise in phase-contrast image. The proposed technique is applied to a sample of 200 μm step height nominally. The recorded off-axis interferograms generated from two different wavelengths are processed to obtain an object wave (amplitude and phase) for each wavelength separately. The independent phase maps are subtracted and a phase map for the beat-wavelength is obtained and converted to height map. The rms values of 10 pixels profiles from the obtained height map are calculated automatically to show the three-dimensional (3D) profile. The experimental results show that the non-coherent noise is reduced by the order of 90% when the rms technique is applied and the uncertainty in measurement has been found to be of the order of 1.5 μm. The proposed technique can provide a simple and real solution for measuring 3D objects having high abrupt height difference.     

射线成像检测中射线源焦点的影响及修正

本文分析了在工业无损检测中射线源焦点对成像质量的影响，讨论了射线源焦点对成像影响的数学模型，以此为基础，设计了相应的焦点修正算法，并给出了处理结果     

Closed-form solutions for a mode III radial matrix crack penetrating a circular inhomogeneity

In this research we address in detail a mode III radial matrix crack penetrating a circular inhomogeneity. One tip of the radial crack lies in the matrix, while the other tip of the radial crack lies in the circular inhomogeneity. In addition the two tips of the crack are mutually image points (or inverse points) with respect to the circular inhomogeneity-matrix interface. First we conformally map the crack onto a unit circle C_a in the new ζ-plane. Meanwhile the inhomogeneity-matrix interface is mapped onto C_b, a part of another circle in the ζ-plane. In addition C_a and C_b intersect at a vertex angle π/2. By using the method of image in the ζ-plane, closed-form solutions in terms of elementary functions are derived for three loading cases: (1) remote uniform antiplane shearing; (2) a screw dislocation located in the unbounded matrix; and (3) a radial Zener–Stroh crack.     

A.第十九届国际高速摄影和光子学会议概况

本文对第19届国际高速摄影与光子学会议做了简介,主要谈到了光机式相机、高速视频技术、全息和干涉计量。     

磁场渗透导体壳的实验研究

本文叙述了测量阶跃脉冲垂直磁场和水平磁场渗透HL-1装置各种比例导体壳时间常数的方法。对空芯和铁芯变压器情况分别做了实验。给出了相应结果。     

Image Space Analysis and Scalarization of Multivalued Optimization

Using a new method based on generalized sections of feasible sets, we obtain optimality conditions for vector optimization of objective multifunctions with multivalued constraints. The authors express their sincere gratitude to Professor F. Giannessi and the referees for comments and valuable suggestions. The second author was partially supported by the Center of Excellence for Mathematics (University of Isfahan).     

Double shearography for engineering metrology: optical and digital approach

This paper presents a double shearographic configuration based on the optical method by using two Michelson interferometers in tandem. The problems associated with the extraction of second order derivatives by optical means and a comparison with the proposed novel approach by digital means are discussed in this paper.     

Optical image encryption using fractional Fourier transform and chaos

We propose a new method for image encryption using fractional Fourier transform and chaos theory. Random phase masks are generated using iterative chaos functions. The input image is combined with the first random phase mask at the object plane and is then transformed using the fractional Fourier transform. After the first fractional Fourier transform, the second random phase mask, again generated by using the chaos functions, is used at the fractional plane. The second fractional Fourier transform operation is then carried out to obtain the encrypted image. Three types of chaos functions have been used: the logistic map, the tent map and the Kaplan–Yorke map. The mean square error and the signal-to-noise ratio between the decrypted image and the input image for the correct order and the incorrect order of the fractional Fourier transform have been calculated. The computer simulations are presented to verify the validity of the proposed technique.     

Deformation and dissipated energies for high cycle fatigue of 2024-T3 aluminium alloy

During the high cycle fatigue of aluminium alloys, an energy dissipation occurs. This dissipation is hard to be estimated because of the high diffusivity of such alloys and the importance of the thermoelasticity effects in comparison with others standard metallic materials (e.g., steels). Nevertheless the study of the energy balance gives valuable information about the nature of deformation mechanisms facilitating the construction of constitutive models associated with the microplasticity and damage of the aluminium alloy. In this work, the different energies involved in the energy balance were deduced from two complementary imaging techniques. The dissipation and thermoelastic sources were derived from an infrared thermography system, while the deformation energy was estimated from a digital image correlation system. Three tests with various loading blocks were carried out and a comparison between deformation and dissipation energies was systematically performed.     

基于数学形态学的表面原子熔融相的 STM图像识别算法

高温扫描隧道显微镜(HT-STM)可以实时原位地捕捉到表面原子的熔化相变过程.在这一原位变温实验中,快速可靠地识别出每帧STM图像中的熔融相十分关键.传统的手工统计方法存在效率低下、随意性大等问题.我们发展出一套基于数学形态学的算法,来自动快速地识别.与人工方法相比,该算法消除了人为主观误差,使确定的边界更加准确、光滑,处理效率提高了266倍.