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691 results on '"Wang, Guoyong"'

28. Medical image encryption algorithm based on hyper‐chaotic system and DNA coding

Author

Mingzhen Li, Shuaihao Pan, Weiming Meng, Wang Guoyong, Zhihang Ji, and Lin Wang

Subjects
Computer engineering. Computer hardware, TK7885-7895, Computer applications to medicine. Medical informatics, R858-859.7
Abstract

Abstract With the international development of the medical service informatisation, medical information sharing has become the key standard to measure the degree of medical informatisation. In this process, it is important to ensure the security of patients' medical information such as patients' records, examination reports, images and so on. In this article, an image encryption scheme based on Secure Hash Algorithm 3 (SHA‐3), DNA coding and high dimensional chaos system is proposed to promote the security level of medical images in information sharing processes such as over the network. First, SHA‐3 algorithm is used to calculate the hash value of the input image, and the result is taken as the initial value of the hyper‐chaotic system. Second, the intensity value of the input image is converted into a serial binary digital stream. Third, the pseudo‐random sequence generated by a 4‐dimensional hyper‐chaotic system is used to perturb the bit stream globally so as to achieve the purpose of hiding the effective information of the input image. During the operation of hyper‐chaotic sequence and DNA sequence, algebraic and complementary operations are performed on DNA encoding values to enhance encryption performance. Finally, simulations have been applied on an open‐source medical image database, and the results demonstrate obvious encryption effectiveness and high security level of the proposed encryption algorithm in the robustness of noise and clipping attacks.

Published
2022
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40. Optical Frequency Transfer on the Order of 10 −19 Fractional Frequency Instability over a 64 m Free-Space Link.

Author

Wang, Guoyong, Lu, Zhangjian, Liang, Xinwen, He, Keliang, He, Yuling, and Ji, Xin

Subjects
ATOMIC clocks, PHASE noise, TIME measurements, OPTICAL fibers, ARTIFICIAL satellites in navigation
Abstract

High-precision time–frequency is widely used in time measurement, satellite navigation, scientific research, and other fields. With the rapid development of optical clock technology, the fractional frequency instability and uncertainty of optical clock have reached 10−18 orders of magnitude, which is expected to contribute to generating the International Atomic Time and may even be used to redefine the "second" in the future. Therefore, the long-distance transfer of time–frequency signals between optical atomic clocks is of great significance. Free-space optical frequency transfer technology is one of the important technologies for solving the space-based optical clock comparison because of its high transfer precision and easy networking characteristics. In order to solve the long-distance space-based optical clock comparison, this paper investigates a free-space active phase noise compensation method using an Acousto-Optic Modulator (AOM), based on the traditional optical fiber phase noise compensation scheme. This new method is more flexible and scalable than the optical fiber time–frequency transfer technology. The optical frequency transfer over a 64 m free-space link is demonstrated. The fractional frequency transfer instability during free running is 9.50 × 10−16 at 1 s, and 4.44 × 10−16 at 2000 s, and the fractional frequency instability after compensation is 7.10 × 10−17 at 1 s, 3.07 × 10−19 at 2000 s, which is about 1–3 orders of magnitude better than that in free running, and provides a feasible scheme for space-based optical clock comparison. [ABSTRACT FROM AUTHOR]

Published
2024
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