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排序方式: 共有221条查询结果,搜索用时 15 毫秒
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The extraction of uranium from aqueous solution is highly desirable for sustaining the increasing demand for environmental safety and nuclear fuel. Herein, we report a strategy using a two-step covalent modification for the synthesis of covalent organic frameworks(COFs) with high-density amidoxime chelate groups at periphery. The introduction of dense amidoxime groups plays a pivotal role in uranium adsorption. The resulting COF exhibits strong affinity with the distribution coefficient of 5.2×104 mL/g and a high adsorption capacity of 319.9 mg/g. The strategy could be expanded to identify and remove different contaminants by introducing special functional groups. 相似文献
53.
Alexander G. Ramm Alexandra B. Smirnova 《Numerical Functional Analysis & Optimization》2013,34(3-4):317-332
A two-step iterative process for the numerical solution of nonlinear problems is suggested. In order to avoid the ill-posed inversion of the Fréchet derivative operator, some regularization parameter is introduced. A convergence theorem is proved. The proposed method is illustrated by a numerical example in which a nonlinear inverse problem of gravimetry is considered. Based on the results of the numerical experiments practical recommendations for the choice of the regularization parameter are given. Some other iterative schemes are considered. 相似文献
54.
Risk process with stochastic income and two-step premium rate 总被引:1,自引:0,他引:1
Ie. Karnaukh 《Applied mathematics and computation》2010,217(2):775-781
In this paper we deal with the risk reserve process with stochastic premium function. We assume that the premiums sizes have exponential distribution with the rate depending on some threshold level. The representation for the discounted defective joint density of surplus and deficit at ruin is obtained. 相似文献
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提出一种通过两幅相移条纹图相减来确定它们之间相移量的方法,进行了理论分析和实验验证。两幅相移条纹图相减并归一化后,得到的相移差分函数是振幅只与相移量有关的正弦函数,可以通过确定该函数最大极值的方法得到振幅,进而计算出相移量。介绍了极值直接查找法和平均法两种实现最大极值测量的方法。由于不使用傅里叶变换,减少了运算时间,既可以用于高空间频率条纹,也可以用于稀疏平行条纹,以及任意花样的条纹。在衬比度因子确定后,用这种方法就能够直接在空域内确定两幅条纹图之间的相移量,通过大量采样点进行统计计算,使结果达到很高的精度。将所得到的结果与用傅里叶变换方法得到的结果进行了比较,表明两种方法得到的结果具有完全相同的精度。 相似文献
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Manabu Sato Jun Iwasaki Toshiaki Ohotaki Yukihiro Hashimoto Naohiro Tanno 《Optical Review》2003,10(5):456-461
We propose a continuous two-step method (CTSM) to obtain an image from two interference images for the measurement time reduction of optical coherence tomography. Image processing is performed for each pixel in CTSM. The calculated signal intensity has an average and standard deviation after processing since the heterodyne beat signal contains the noise in the measurements. We assume that the heterodyne beat signal contains the random noise in simulations and calculate the influence of the normalized standard deviation (NSD = standard deviation/average) on the random noise intensity for both CTSM and the conventional three-step method (TSM). We found that the NSD of the CTSM is only 1.4 times greater than that of the TSM despite processing only two images. 相似文献
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为了实现干涉仪出射准直波前的重构,提出了基于波长调谐移相的横向剪切干涉技术。干涉仪出射波前分别经楔板的前后表面反射,通过角锥棱镜返回后在干涉仪CCD上形成剪切干涉条纹。采用波长移相方法提取剪切干涉条纹的相位信息从而实现准直波前重构。分析相对剪切比对波面重构精度的影响,推导相对剪切比和其影响因素间的关系公式,给出波长移相中光程差常数分量的估算方法。测量干涉仪的三组出射波前,波前的峰谷值分别为3.22λ、2.10λ、0.83λ。该方法简化了传统测量干涉仪准直波前的横向剪切干涉装置,提高了测量精度,特别适合于测量波长移相干涉仪的出射波前。 相似文献
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Hand shake blurry image is a common phenomenon in our daily life. In this paper, a novel blind deconvolution scheme is proposed to recover a single hand shake blurry image. The algorithm is subdivided into two main stages, kernel estimation stage and non-blind deconvolution stage. In the kernel estimation stage, we propose a cost function taking a selected map into consideration. In the non-blind decovolution stage, another cost function is designed using image derivatives prior. We also present an adaptive kernel size selection method instead of traditional manual selection. Extensive experiments on real world blurry images are conducted to demonstrate the performance of our algorithm. 相似文献