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Wyszukujesz frazę "Zhou, Z" wg kryterium: Autor


Wyświetlanie 1-10 z 10
Tytuł:
Image encryption combining discrete fractional angular transform with Arnold transform in image bit planes
Autorzy:
Zhou, Z.
Yu, J.
Liao, Q.
Gong, L.
Powiązania:
https://bibliotekanauki.pl/articles/173704.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Arnold transform
bit plane
discrete fractional angular transform
image encryption algorithm
Opis:
A new image encryption algorithm by using a discrete fractional angular transform and Arnold transform in image bit planes is investigated. In the image encryption algorithm, the original image is encrypted by the Arnold transform in image bit planes firstly, and then the resulting image is encrypted by the discrete fractional angular transform further. The key of the image encryption algorithm includes the parameters of the Arnold transform and the order of the discrete fractional angular transform. It is shown that the proposed image encryption algorithm is of high security and strong enough to counteract some conventional image attack manners.
Źródło:
Optica Applicata; 2018, 48, 2; 225-236
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Near-field multiple optical trapping using high order axially symmetric polarized beams
Autorzy:
Zhou, Z
Tan, Q
Zhu, L
Yang, C
Powiązania:
https://bibliotekanauki.pl/articles/174886.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optical trapping
surface plasmon polaritons
axially symmetric polarized beams
Opis:
The near-field multiple optical trapping using high order axially symmetric polarized beams (ASPBs) is studied for the first time. First, a near-field optical trapping scheme is proposed based on the Kretschmann–Raether configuration, and surface plasmon polaritons (SPPs) field distributions excited by incident ASPBs are calculated, which present a multi-focal-spot pattern and the size of spots is much smaller than that of the diffraction limitation. Then, the gradient forces on Rayleigh dielectric particles formed by the multi-focal-spot focused field are computed, which indicates that multiple ultra-small particles with the refractive index higher than that of the ambient medium can be trapped simultaneously on the metal surface. The number and size of trapped particles can be manipulated by flexibly modifying the polarization order of incident beams, which is expected to enhance the capability of traditional optical trapping systems and provide a solution for massively parallel optical trapping of nanometer-sized particles.
Źródło:
Optica Applicata; 2013, 43, 2; s. 287-296
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Image encryption algorithm by using the logistic map and discrete fractional angular transform
Autorzy:
Yu, J.
Li, Y.
Xie, X.
Zhou, N.
Zhou, Z.
Powiązania:
https://bibliotekanauki.pl/articles/173813.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
image encryption
logistic map
discrete fractional angular transform
Opis:
A new image encryption scheme based on logistic map and discrete fractional angular transform has been proposed. In the proposed scheme, the original image is encrypted with the random sequence generated by the logistic map, and the encrypted image is subsequently processed by the discrete fractional angular transform, which produces the ciphertext after double encryptions. The parameters of the logistic map and the order of the discrete fractional angular transform serve as the main keys of the image encryption algorithm. Simulation results show that the proposed image encryption algorithm can effectively resist the attacks of statistical analysis, and has acceptable encryption effect and security.
Źródło:
Optica Applicata; 2017, 47, 1; 141-155
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
One step purification of impurities in the leachate of weathered crust elution-deposited rare earth ores
Autorzy:
Zhou, F.
Feng, J.
Wang, Z.
Xu, Y.
Zhang, Z.
Chi, R.
Powiązania:
https://bibliotekanauki.pl/articles/110333.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
leachate
weathered crust
rare earth ore
leachate purification
precipitation
Opis:
It is necessary to control and reduce the high content of Al3+, Cu2+ and Pb2+ ions in the leachate of weathered crust elution-deposited rare earth ore to facilitate the rare earth recovery and the quality of rare earth products. Neither NH4HCO3 nor Na2S are suitable for removal of all impurity ions and meanwhile maintain high rare earth recovery. Conventionally, NH4HCO3 is firstly adopted to remove Al3+, and then Cu2+ and Pb2+ are removed by using Na2S. This two steps purification process is quite long and results in lots of complication in operation. In this paper, a one-step purification by using the compound of NH4HCO3 and Na2S was proposed to remove Al3+, Cu2+ and Pb2+. The results showed that after purification 89% Cu, 92% Pb and 74% Al were removed from the leachate solution by using 0.1 M compound of NH4HCO3/Na2S, while maintaining 89% rare earth. The optimal purification parameters were: volume ratio of NH4HCO3 to Na2S of 9:1, volume ratio of compound to leachate of 0.05:1, precipitation time of 30 min.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 1188-1199
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deflectometry for phase retrieval using a composite fringe
Autorzy:
Liu, T.
Zhou, C.
Liu, Y
Si, S
Lei, Z.
Powiązania:
https://bibliotekanauki.pl/articles/173892.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
wavefront measurement
fringe analysis
phase retrieval
fast Fourier transform (FFT)
multifrequency heterodyne principle
Opis:
An improved deflectometry for wavefront measurement using a composite fringe is proposed to reduce the projection fringes and improve the accuracy. The single composite fringe contains four fringes in different directions. It goes through the tested objects and then is captured by a CCD camera. Two high frequency orthogonal fringe patterns and two single period orthogonal fringe patterns can be obtained from the composite fringe by fast Fourier transform. The unwrapping of the wrapped phase of the high frequency fringe is accomplished by the corresponding single period fringe using a heterodyne method. The wavefront is reconstructed by the integration of partial derivatives. Using only one fringe, the proposed method is more applicable to dynamic wavefront measurement. The experimental results demonstrate that the proposed method can retrieve the complex wavefronts more accurately.
Źródło:
Optica Applicata; 2014, 44, 3; 451-461
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Depth-resolved measurement of the compression displacement fields on the front and rear surfaces of an epoxy sample
Autorzy:
Zhang, W.
Dong, B.
He, Z.
Xie, S.
Zhou, Y.
Powiązania:
https://bibliotekanauki.pl/articles/174399.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
depth-resolved measurement
compression displacement field
wavenumber-scanning interferometry
epoxy
Opis:
Compression is one of the typical parameters measured in material mechanics. In this research, the compression displacement fields on the front and rear surfaces of an epoxy sample are measured by using a tilt depth-resolved wavenumber-scanning Michelson interferometer. The light source is a distributed feedback laser diode, the wavenumber of which can be modulated to about 1.017 × 104 m–1 by the temperature without mode hopping. A random-sampling Fourier transform is designed to evaluate the phase differences before and after the applied loads. Experimental results show that the depth-resolved measurement of the compression displacement field is of high accuracy. It can be used to analyze force propagation inside resin-based composites.
Źródło:
Optica Applicata; 2018, 48, 2; 311-323
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnified holographic projection based on spatial light modulators
Autorzy:
Su, Y.
Cai, Z.
Shi, L.
Zhou, F.
Chen, H.
Wu, J.
Powiązania:
https://bibliotekanauki.pl/articles/174247.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
holographic display
spatial light modulators
computer-generated holograms
magnified holographic projection
Opis:
In this paper, a magnified holographic projection based on spatial light modulators is proposed and implemented by combining four magnification methods, including similarity principle of Fourier transform, spatial division, digital lens, and image splicing methods. The Fourier holographic display system is constructed for the experimental verification of the proposed methods. With such four methods of holographic magnification, the reconstruction image can be magnified to 10 × 5 times in two-dimensional directions, which is verified by the experiments. Furthermore, the undesirable light of holographic projection is eliminated by encoding the linear phase onto the computer-generated holograms. The experimental results prove that the proposed system can realize magnified holographic projection with good reconstructed quality, which provides a promising potential for the dynamic holographic projector.
Źródło:
Optica Applicata; 2018, 48, 4; 589-600
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improved method for phase wraps reduction in profilometry
Autorzy:
Du, G.
Wang, M.
Zhou, C.
Si, S.
Li, H.
Lei, Z.
Li, Y.
Powiązania:
https://bibliotekanauki.pl/articles/173793.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
phase unwrapping
zero-padding
Fourier transform
carrier-frequency
profilometry
Opis:
In order to completely eliminate, or greatly reduce the number of phase wraps in 2D wrapped phase map, Gdeisat and co-workers proposed an algorithm, which uses shifting the spectrum towards the origin. But the spectrum can be shifted only by an integer number, meaning that the phase wraps reduction is often not optimal. In addition, Gdeisat’s method will take much time to make the Fourier transform, inverse Fourier transform, select and shift the spectral components. In view of the above problems, we proposed an improved method for phase wraps elimination or reduction. First, the wrapped phase map is padded with zeros, the carrier frequency of the projected fringe is determined by high resolution, which can be used as the moving distance of the spectrum. And then realize frequency shift in spatial domain. So it not only can enable the spectrum to be shifted by a rational number when the carrier frequency is not an integer number, but also reduce the execution time. Finally, the experimental results demonstrated that the proposed method is feasible.
Źródło:
Optica Applicata; 2017, 47, 2; 295-306
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
One shot profilometry using iterative two-step temporal phase-unwrapping
Autorzy:
Du, G.
Wang, M.
Zhou, C.
Si, S.
Li, H.
Lei, Z.
Li, Y.
Powiązania:
https://bibliotekanauki.pl/articles/173912.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
phase unwrapping
composite fringe pattern
Fourier transform
two-step temporal phase-unwrapping
Opis:
This paper reviews two techniques that have been recently published for three-dimensional profilometry and proposes one shot profilometry using iterative two-step temporal phase-unwrapping by combining the composite fringe projection and the iterative two-step temporal phase unwrapping algorithm. In temporal phase unwrapping, many images with different frequency fringe pattern are needed to project, which would take much time. In order to solve this problem, Ochoa proposed a phase unwrapping algorithm based on phase partitions using a composite fringe. However, we found that the fringe order determined through the construction of phase partitions tended to be imprecise. Recently, we proposed an iterative two-step temporal phase unwrapping algorithm, which can achieve high sensitivity and high precision shape measurement. But it needs multiple frames of fringe images which would take much time. In order to take into account both the speed and accuracy of three-dimensional shape measurement, we get a new, and more accurate unwrapping method based on a composite fringe pattern by combining these two techniques. This method not only retains the speed advantage of Ochoa’s algorithm, but also greatly improves its measurement accuracy. Finally, the experimental evaluation is conducted to prove the validity of the proposed method.
Źródło:
Optica Applicata; 2017, 47, 1; 97-110
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessing soil environmental capacity on different land uses in a suburban area of Chengdu, China
Autorzy:
Yang, W.-L.
Zhou, W.-Y.
Wan, W.-X.
Gou, S.-Z.
Zhang, J.
Deng, S.-H.
Shen, F.
Wang, Y.-J.
Yang, H.
Luo, L.
Powiązania:
https://bibliotekanauki.pl/articles/207670.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
China
soil pollution
heavy metals
soil
vegetables
Chiny
zanieczyszczenie gleby
metale ciężkie
gleba
warzywa
Opis:
Wenjiang (China) is the area which undertakes high-intensity planting activities. Additionally, the soil environmental capacity has been a hot area of research as it plays a key role in environmental protection planning, environmental impact assessment and sustainable development. In this paper, the static model of soil environmental capacity is employed to investigate the distribution of residual soil environmental capacity in Wenjiang. The results show that the soil environmental capacity of mercury is the largest for industrial land while it is the lowest in garlic-rice planting areas; the soil environmental capacity of arsenic is the largest in city construction land while it is the lowest in ecological conservation zone; the soil environmental capacity of lead is the largest in city construction land while it is the lowest in garlic-rice planting areas; and the soil environmental capacity of chromium is the largest in city construction land while it is the lowest in garlic-rice planting areas.
Źródło:
Environment Protection Engineering; 2019, 45, 2; 55-67
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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