In situ analysis of multi-twin morphology and growth using synchrotron polychromatic X-ray microdiffraction

Synchrotron polychromatic X-ray microdiffraction（micro-XRD） was applied to study in situ deformation twinning of commercially AZ31（Mg-3Al-1Zn） strip subjected to uniaxial tension.The morphology and growth of twins were analyzed in situ under the load level from 64 to 73 MPa.The X-ray microdiffraction data,collected on beamline 12.3.2 at the Advanced Light Source,were then used to map an area of 396μm x 200μm within the region of interest.The experimental set-up and X-ray diffraction microscopy with a depth resolution allow the position and orientation of each illuminated grain to be determined at the submicron size.A list of parent grains sorted by crystallographic orientation were selected to examine their twinning behavior.The results depict twin variant selection,local misorientation fluctuation and mosaic spread for multi-twins within the same parent grain.As load increases,the amplitude of misorientation fluctuation along twin trace keeps increasing.This is attributable to the accumulation of geometrically necessary dislocations.

Spectral anomalies and spectral switches of partially coherent and polychromatic light diffracted at an aperture

Based on the propagation theory of partially coherent light in the space-frequency domain, the anomalous spectral behavior and spectral switches in the far field of partially coherent and polychromatic light diffracted at an aperture are studied. It is shown that, as compared with spatially fully coherent and polychromatic light whose spectral anomalies are induced only by aperture diffraction, the spectral anomalies and spectral switches of partially coherent and polychromatic light depend on the aperture diffraction, spatial correlationβ and bandwidth of the original spectrum. Detailed numerical calculations are made to illustrate the behavior of spectral switches of partially coherent and polychromatic light, and the results for spatially fully coherent and polychromatic light are treated as a special case ofβ=1 and included in our theory.

High quality multi-focus polychromatic composite image fusion algorithm based on filtering in frequency domain and synthesis in space domain

A novel multi-focus polychromatic image fusion algorithm based on filtering in the frequency domain using fast Fourier transform(FFT) and synthesis in the space domain(FFDSSD) is presented in this paper.First,the original multi-focus images are transformed into their frequency data by FFT for easy and accurate clarity determination.Then a Gaussian low-pass filter is used to filter the high frequency information corresponding to the image saliencies.After an inverse FFT,the filtered images are obtained.The deviation between the filtered images and the original ones,representing the clarity of the image,is used to select the pixels from the multi-focus images to reconstruct a completely focused image.These operations in space domain preserve the original information as much as possible and are relatively insensitive to misregistration scenarios with respect to transform domain methods.The polychromatic noise is well considered and successfully avoided while the information in different chromatic channels is preserved.A natural,nice-looking fused microscopic image for human visual evaluations is obtained in a dedicated experiment.The experimental results indicate that the proposed algorithm has a good performance in objective quality metrics and runtime efficiency.

Roughness Measurements with Polychromatic Speckles on Tilted Surfaces

Surface light scattering enables contactless and fast measurements of surface roughness.A surface inclination alters the direction of the scattering beam and thus the measured surface roughness is calculated from the detected intensity distribution.Hence,an accurate sensor-surface alignment is necessary.In order to achieve tilt-independent roughness measurements,a model-based evaluation approach for polychromatic speckle patterns is presented.By evaluating the shape of the superposed speckles,which occur for polychromatic illumination,with regard to the distance to the scattering centre,surfaces with an Sa roughness value in the range of 0.8-3.2μm are measurable.Experimental investigations demonstrate that the influence of a surface tilt up to±1.25°on the roughness measurement is reduced by 90%.As a result,the robustness of the polychromatic speckle roughness measurement is improved,which allows to speed up the adjustment of the measurement system or the surface sample,respectively.

基于多色蚁群的柔性测试系统测试资源匹配

柔性测试系统是测试需求导向的客户化定制系统,其组建和运行的前提是如何根据具体的测试任务需求匹配出能够完成测试任务的最优测试资源集合.本文首先在面向信号描述测试任务需求和测试资源能力的基础上,求得测试任务的信号完整特征集合,然后对匹配问题的传统二分图模型进行扩展,给出测试资源匹配的多色加权二分图描述模型.结合蚁群算法,提出了柔性测试系统资源匹配的多色蚁群算法,最后通过实际的资源匹配实例说明了模型的有效性和算法的优越性.

Holographic Imaging of Argon Plasma Images

A coding and decoding process of argon plasma images using digital holography is proposed. The digital Fourier holography is applied to two images of matrix dimensions 512 × 512 pixels. The decoded images are improved using wiener filtering techniques. We have constructed three basic color images of the original image which is useful to extract the thermal distribution of the plasma image. Also, the profiles of the reconstructed images are checked showing better smooth profiles using wiener filter. The Mat-lab code is applied in the operation of image processing using Fourier techniques.

Complete temporal characterization of a single photon

Precise information about the temporal mode of optical states is crucial for optimizing their interaction efficiency between themselves and/or with matter in various quantum communication devices.Here we propose and experimentally demonstrate a method of determining both the real and imaginary components of a single photon’s temporal density matrix by measuring the autocorrelation function of the photocurrent from a balanced homodyne detector at multiple local oscillator frequencies.We test our method on single photons heralded from biphotons generated via four-wave mixing in an atomic vapor and obtain excellent agreement with theoretical predictions for several settings.