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Wyszukujesz frazę "Qin, Z." wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
Accurate gradient computations at interfaces using finite element methods
Autorzy:
Qin, F.
Wang, Z.
Ma, Z.
Li, Z.
Powiązania:
https://bibliotekanauki.pl/articles/330659.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
elliptic interface problem
gradient flux computation
IFEM
mixed FE formulation
computational tube
Opis:
New finite element methods are proposed for elliptic interface problems in one and two dimensions. The main motivation is to get not only an accurate solution, but also an accurate first order derivative at the interface (from each side). The key in 1D is to use the idea of Wheeler (1974). For 2D interface problems, the point is to introduce a small tube near the interface and propose the gradient as part of unknowns, which is similar to a mixed finite element method, but only at the interface. Thus the computational cost is just slightly higher than in the standard finite element method. We present a rigorous one dimensional analysis, which shows a second order convergence order for both the solution and the gradient in 1D. For two dimensional problems, we present numerical results and observe second order convergence for the solution, and super-convergence for the gradient at the interface.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2017, 27, 3; 527-537
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fully-phase optical image encryption in diffractive-imaging scheme with QR-code-based random illumination
Autorzy:
Wang, Z.
Zhang, Y.
Gong, Q.
Li, S.
Qin, Y.
Powiązania:
https://bibliotekanauki.pl/articles/174126.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optical encryption
diffractive imaging
fully phase
phase retrieval algorithm
Opis:
Based on a fully phase encoding and phase retrieval algorithm, a diffractive-imaging-based optical encryption scheme with random illumination is proposed. In the encryption process, a QR code image is placed in the optic path to modulate the incident light and thus generate a random illumination, which has been demonstrated to enable the proposed scheme to resist the multi-slice ptychographic phase retrieval algorithm attack. The plaintext is phase-encoded, and then encrypted by two random phase masks. The diffraction pattern in the output plane is recorded as ciphertext by a CCD camera. For decryption, an iterative phase retrieval algorithm with median filtering operation is implemented. Simulation results demonstrate the effectiveness, security, and robustness of the proposal.
Źródło:
Optica Applicata; 2017, 47, 2; 233-243
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical image encryption by using diffractive imaging with special constraint in the input plane
Autorzy:
Wang, Z.
Wang, H.
Yang, X.
Zhang, P.
Hou, C.
Qin, Y.
Powiązania:
https://bibliotekanauki.pl/articles/173781.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optical encryption
diffractive imaging
bilinear interpolation
Opis:
In order to simplify the optical setup and the encryption process, a diffractive-imaging-based optical encryption system using a single diffraction pattern is proposed. A predesigned binary mask is placed before the plaintext in the encryption process, and three randomly distributed phase only masks are placed in the optical path. Only one diffraction pattern needs to be recorded as ciphertext by CCD. In the decryption process, an iterative phase retrieval algorithm is applied, in which the predesigned binary mask acts as a support constraint in the input plane. After the iterative process, an interpolation operation for the zero-valued pixels is also implemented. The effectiveness and robustness of the proposal are demonstrated by numerical simulation results.
Źródło:
Optica Applicata; 2016, 46, 1; 57-69
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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