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71.
In present times, barcode decoders on mobile phones can extract the data content of QR codes. However, this convenience raises concerns about security issues when using QR codes to transmit confidential information, such as e-tickets, coupons, and other private data. Moreover, current secret hiding techniques are unsuitable for QR code applications since QR codes are module-oriented, which is different from the pixel-oriented hiding manner. In this article, we propose an algorithm to conceal confidential information by changing the modules of the QR Code. This new scheme designs the triple module groups based on the concept of the error correction capability. Additionally, this manner can conceal two secret bits by changing only one module, and the amount of hidden confidential information can be twice the original amount. As a result, the ordinary data content (such as URL) can be extracted correctly from the generated QR code by any barcode decoders, which does not affect the readability of scanning. Furthermore, only authorized users with the secret key can further extract the concealed confidential information. This designed scheme can provide secure and reliable applications for the QR system. 相似文献
72.
Shi Shuangning Shang Yong Liang Qinglin Liang Bin 《电子科学学刊(英文版)》2007,24(6):812-814
The real Direction Of Arrival (DOA) varies with time in mobile communication system. In such situation, the performance of conventional beamformers will be degraded obviously. Quantum Signal Processing (QSP) beamformer is insensitive to DOA errors, thus it can achieve stable output performance in such circumstance. This letter verified the effectiveness and feasibility of the QSP beamformer by simulation results. 相似文献
73.
本文主要讲述了视放回路的原理、调整及其对彩管会聚、色平衡的影响.为解决视放回路过长而引起的视频延迟现象,专门设计了一套视频放大板,其中包括了预视放回路、视频延迟回路、视频放大输出部分及EK恒压源回路等. 相似文献
74.
Jing Wen Jian Su Yinnian He Hongbin Chen 《Numerical Methods for Partial Differential Equations》2021,37(1):383-405
In this paper, a semi‐discrete scheme and a fully discrete scheme of the Stokes‐Biot model are proposed, and we analyze the semi‐discrete scheme in detail. First of all, we prove the existence and uniqueness of the semi‐discrete scheme, and a‐priori error estimates are derived. Then, we present the same conclusions for the fully discrete scheme. Finally, under both matching and non‐matching meshes some numerical tests are given to validate the analysis of convergence, which well support the theoretical results. 相似文献
75.
Weak Galerkin finite element methods combined with Crank-Nicolson scheme for parabolic interface problems 下载免费PDF全文
This article is devoted to the a priori error estimates of the fully discrete Crank-Nicolson approximation for the linear parabolic interface problem via weak Galerkin finite element methods (WG-FEM). All the finite element functions are discontinuous for which the usual gradient operator is implemented as distributions in properly defined spaces. Optimal order error estimates in both $L^{\infty}(H^1)$ and $L^{\infty}(L^2)$ norms are established for lowest order WG finite element space $({\cal P}_{k}(K),\;{\cal P}_{k-1}(\partial K),\;\big[{\cal P}_{k-1}(K)\big]^2)$. Finally, we give numerical examples to verify the theoretical results. 相似文献
76.
77.
T. Håvie 《BIT Numerical Mathematics》1970,10(3):277-294
Some quadrature formulae using the derivatives of the integrand are discussed. As special cases are obtained generalizations of both the ordinary and the modified Romberg algorithms. In all cases the error terms are expressed in terms of Bernoulli polynomials and functions. 相似文献
78.
张红玉 《数学的实践与认识》2010,40(11)
针对于微分方程数值解,介绍了一种新的误差估计方法.方法证实了伪谱方法具有精度高速度快的优点,进而引出了修正的伪谱方法. 相似文献
79.
I. Grabec 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(1):129-135
A physical law is represented by the probability distribution of a measured variable. The probability density is described
by measured data using an estimator whose kernel is the instrument scattering function. The experimental information and data
redundancy are defined in terms of information entropy. The model cost function, comprised of data redundancy and estimation
error, is minimized by the creation-annihilation process.
Received 24 February 2000 and Received in final form 21 February 2001 相似文献
80.
李晓康 《纯粹数学与应用数学》2010,26(5):776-784
为对基金净值数据进行建模,根据基金净值样本数据的尾部特点,建立极大,极小值分布的GPD模型,运用POT方法确定临界值,进而对参数进行估计,并对模型进行检验.最后,运用建立的模型对一些极值点进行预测.所得结果很好地描述了数据特点,对极值点的预测符合实际. 相似文献