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排序方式: 共有108条查询结果,搜索用时 15 毫秒
1.
Bin Pan Dinghua Xu Yinghong Xu Yue Yu 《Mathematical Methods in the Applied Sciences》2017,40(4):957-969
This paper investigates an inverse problem for parabolic equations backward in time, which is solved by total‐variation‐like (TV‐like, in abbreviation) regularization method with cost function ∥ux∥2. The existence, uniqueness and stability estimate for the regularization problem are deduced in the linear case. For numerical illustration, the variational adjoint method, which presents a simple method to derive the gradient of the optimization functional, is introduced to reconstruct the unknown initial condition for both linear and nonlinear parabolic equations. The conjugate gradient method is used to iteratively search for the optimal approximation. Numerical results validate the feasibility and effectiveness of the proposed algorithm. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
2.
We report an electro-photo double modulation of the fermi level in a WSe2/graphene heterojunction. The heterojunction exhibits high ION/IOFF ratio (~103) in transfer characteristic in dark and distinct rectification behavior in output characteristic under light illumination, respectively. Time-dependent photoresponse reveals that the heterojunction has a considerable potential in the application of photodetection. Interestingly, an exotic current peak is observed in transfer characteristic under light illumination. This novel behavior is attributed to the tunable fermi level at the WSe2/graphene heterojunction by electro-photo double modulation. The results may be helpful to develop tunable photovoltaic optoelectronics based on van der Waals heterojunctions. 相似文献
3.
Anisotropic total variation minimization approach in in-line phase-contrast tomography and its application to correction of ring artifacts 下载免费PDF全文
In-line phase-contrast computed tomography(IL-PC-CT) imaging is a new physical and biochemical imaging method.IL-PC-CT has advantages compared to absorption CT when imaging soft tissues. In practical applications, ring artifacts which will reduce the image quality are commonly encountered in IL-PC-CT, and numerous correction methods exist to either pre-process the sinogram or post-process the reconstructed image. In this study, we develop an IL-PC-CT reconstruction method based on anisotropic total variation(TV) minimization. Using this method, the ring artifacts are corrected during the reconstruction process. This method is compared with two methods: a sinogram preprocessing correction technique based on wavelet-FFT filter and a reconstruction method based on isotropic TV. The correction results show that the proposed method can reduce visible ring artifacts while preserving the liver section details for real liver section synchrotron data. 相似文献
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用于航摄测量,大地测量和星体测量等方面的精密光学仪器,在出厂前必须进行完整地校准和检验,以便确定它们的焦距、畸变量,并且在允许的范围之内给出畸变量的修正值。本文介绍了利用高精度光学经纬仪来测量跟踪电视光学系统的焦距和畸变,并对测量精度进行了分析。指出了测量中需要注意的几个主要问题。 相似文献
6.
Arvind Kumar Misra Rajanish Kumar Rai 《Mathematical Methods in the Applied Sciences》2019,42(4):1262-1282
TV and radio advertisements are widely acknowledged as important interventions in raising issues of public health care and play promising role to control the infection through propagating awareness among the individuals. In this paper, a nonlinear susceptible‐infected‐susceptible (SIS) model is proposed and analyzed to see the impacts of TV and radio advertisements on the spread of influenza epidemic. In the model formulation, it is assumed that the susceptible individuals contract infection through the direct contact with infected individuals. The information regarding the protection against the disease is propagated via TV and radio advertisements, and their growth rates are assumed to be proportional to the fraction of infected individuals. However, the growth rate of TV advertisements decreases with the increase in number of aware individuals. The information broadcasted through TV and radio advertisements induces behavioral changes among the susceptible individuals, and they form an isolated aware class. The epidemiological feasible equilibria, their stability properties, and direction of bifurcation are discussed. The expression for modified basic reproduction number is obtained. The model analysis shows that the dissemination rate of awareness among susceptible individuals due to TV and radio advertisements and baseline number of TV and radio advertisements have potential to reduce the epidemic peak and, thus, control the spread of infection. Further, the analytical findings are well supported through numerical simulation. 相似文献
7.
Michael Breuß Andrea Bürgel Thomas Brox Thomas Sonar Joachim Weickert 《Numerical Algorithms》2006,41(1):79-101
The singular diffusion equation called total variation (TV) flow plays an important role in image processing and appears to
be suitable for reducing oscillations in other types of data. Due to its singularity for zero gradients, numerical discretizations
have to be chosen with care. We discuss different ways to implement TV flow numerically, and we show that a number of discrete
versions of this equation may introduce oscillations such that the scheme is in general not TV-decreasing. On the other hand,
we show that TV flow may act self-stabilising: even if the total variation increases by the filtering process, the resulting
oscillations remain bounded by a constant that is proportional to the ratio of mesh widths. For our analysis we restrict ourselves
to the one-dimensional setting. 相似文献
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9.
本文简述了用电视摄象机进行工业尺寸测量的微分法与拟合法的基本原理,同时详细的讨论了各自所能达到的精度极限。本文用实验验证了理论计算的结果,最后对二维工件测量时,如何根据工件的不同形状与位置以及光学系统的特点,提出了在测量时工件的放置应该注意的问题以及对工件拐角处如何进行处理的方法。 相似文献
10.
The use of a TV camera with a standard pyroelectric tube for imaging continuous submillimeter (submm) waves is described. The spectral sensitivity of such pyroelectric vidicon has been measured. The results of experiments on diffraction and interference using submm laser radiation are presented. For the first time, submm images of different objects have been obtained with the aid of a pyroelectric vidicon. It has been shown that a pyroelectric TV camera can be effectively employed in various laser studies as well as in submm imagery technique. 相似文献