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921.
Based on the whole process of the recording and reconstruction of digital holography, we study the formation cause of speckle noise in its reconstructed image and acquire the conclusion that the small size of hologram aperture diffraction aggravates the speckle noise of reconstructed image and the speckle noise has been one of primary noise sources in the reconstruction process. In order to reduce the speckle noise resulting from little hologram aperture diffraction, we set an appropriate aperture function matching the recording parameter and aperture size of hologram and deconvolve the reconstructed image with it. The validity has been proved in theory and experiment. Therefore, it offers a brand-new thought and practical way to reduce the speckle noise in the reconstructed image of digital holography. 相似文献
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924.
制备了一种对整个可见光波段都敏感的光全息存储材料,并研究了该材料的透过率、衍射效率、灵敏度等全息特性.用He-Ne激光器633 nm和Ar+ 激光器514 nm,488 nm,476 nm四种波长的光曝光,材料的饱和衍射效率最大为66%,最小为48%;最高灵敏度为8.06×10-3 cm2/mJ.最高折射率调制度为4.22×10-4.用多波长存储时,不同波长的光可存储多幅全息图,且再现图像清晰.结果表明,该材料是较好的高密度数字全息存储材料. 相似文献
925.
光谱分析采样数据重建原始信号 总被引:2,自引:0,他引:2
用光谱分析方法分析信号的采样与恢复。用三个改进的升余弦脉冲构造对称的限带频谱F(ω),经理论推导获得时域信号f(t)。采用梳状函数δT(t)对f(t)采样,调节T值,获得Shannon采样。应用快速傅里叶变换,计算采样的频谱Fd(ω),比较计算频谱Fd(ω)与限带频谱F(ω)的差别,讨论由采样频谱Fd(ω)重建f(t)的方法。结果发现:计算频谱Fd(ω)与限带频谱F(ω)非常相似,由采样数据可以在时域直接重建原始信号,而由频谱数据经快速逆傅里叶变换,同样能准确重建原始信号。因此,信号存储,既可以存储其采样信号,也可以存储采样信号的数字频谱。 相似文献
926.
为满足液滴式数字聚合酶链式反应(PCR)技术对扩增反应过程中稳定保存液滴以及反应后高效检测的核心需求,构建了一种具有过滤气泡和增强荧光信号功能的液滴式数字聚合酶链式反应芯片.该芯片可在10 min内产生20多万个半径约为21μm的液滴.利用"玻璃天花板"的方式构建了独立于芯片主体材料的液滴收集腔,为液滴提供稳定的保存与反应环境;还构建了过滤结构,可有效过滤混入液相中的空气,提高芯片鲁棒性.同时,在液滴收集腔中引入反射层,增强荧光信号,使单个视野荧光成像时间缩短约40%,提高了检测效率.利用该芯片定量检测EGFR基因第21号外显子,检测信号与DNA浓度在101~105copies/μL范围内呈现良好的线性关系(R2=0.998).该方案在载玻片大小的芯片上实现了液滴产生、PCR扩增和荧光信号读取,并具有较高的鲁棒性与检测效率,在核酸检测等方面具有应用潜力. 相似文献
927.
《Particuology》2023
The force chain is the core of the multi-scale analysis of granular matter. Accurately extracting the force chain information among particles is of great significance to the study of particle mechanics and geological hazards caused by particle flow. However, in the photoelastic experiment, the precise identification of the branching points of force chains has not been effectively realized. Therefore, this study proposes an automatic extraction method of force chain key information. First, based on the Hough transform and the Euclidean distance, a particle geometric information identification model is established and geometric information such as particle circle center coordinates, radius, contact point location, and contact angle is extracted. Then, a particle contact force information identification model is established following the color gradient mean square method. The model realizes the rapid calibration and extraction of a large number of particle media contact force information. Next, combined with the force chain composition criterion and its quasilinear feature, an automatic extraction method of force chain information is established, which solves the problem of the accurate identification of the force chain branch points. Finally, in the photoelastic experiment of ore drawing from a single drawpoint, the automatic extraction method of force chain information is verified. The results show that the macroscopic distribution of force chains during ore drawing from a single drawpoint is left–right symmetrical. Strong force chains are mostly located on the two sides of the model but in small numbers and they mainly develop vertically. Additionally, the ends are mostly in a combination of Y and inverted Y shapes, while the middle is mostly quasilinear. Weak force chains are abundant and mostly distributed in the middle of the model, and develop in different directions. The proposed extraction method accurately extracts the force chain network from the photoelastic experiment images and dynamically characterizes the force chains of granular matter, which has significant advantages in particle geometry information extraction, force chain branch point discrimination, force chain retrieval, and force chain distribution and its azimuthal characterization. The results provide a scientific basis for studying the macroscopic and microscopic mechanical parameters of granular matter. 相似文献
928.
Dr. Clara Patricia Marshall Dr. Julia Schumann Dr. Annette Trunschke 《Angewandte Chemie (International ed. in English)》2023,62(30):e202302971
Heterogeneous catalysis is an important area of research that generates data as intricate as the phenomenon itself. Complexity is inherently coupled to the function of the catalyst and advance in knowledge can only be achieved if this complexity is adequately captured and accounted for. This requires integration of experiment and theory, high data quality and quality control, close interdisciplinary collaboration, and sharing of data and metadata, which is facilitated by the application of joint data management strategies. This Viewpoint Article first discusses the potential of a digital transition in catalysis research. Then, a summary of the current status in terms of data infrastructure in heterogeneous catalysis is presented, defining the various types of (meta-) data, from catalyst synthesis to functional analysis. Finally, an already implemented working concept for local data acquisition and storage is introduced and the benefits and further development directions for catalysis data use and sharing are discussed. 相似文献
929.
Digital Cofibration and Digital Lusternik-Schnirelmann Category in the Sense of Subdivision
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In this paper, using the notion of subdivision, the authors generalize the definition of cofibration in digital topology and show that this kind of cofibration is injective in the sense of subdivision. Meanwhile, they give the necessary condition under which a digital map is a cofibration. Furthermore, they consider the Lusternik-Schnirelmann category of digital maps in the sense of subdivision and give several fundamental homotopy properties about it. 相似文献