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204 results on '"Zhu, Zhenmin"'

15. Reinforcement learning based group key agreement scheme with reduced latency for VANET

Author

XU Tangwei, ZHANG Hailu, LIU Chuhuan, XIAO Liang and ZHU Zhenmin

Subjects
vanet, group key agreement, reinforcement learning, Electronic computers. Computer science, QA75.5-76.95
Abstract

Key agreement scheme of vehicle ad hoc networks (VANET) determines the privacy and security against user identity-based attacks, such as spoofing attack. The existing work updates the group shared key at a fixed frequency, which increases the processing latency of the key updates and the encryption and decryption of group communication. A reinforcement learning based dynamic key agreement scheme was proposed to enable the group cluster head to optimize the key update frequency and key length. This scheme optimizes the calculation latency of encryption and decryption based on the number of surrounding vehicles, the previous key update records without the knowledge of the traffic flow model and the access-driven cache attack model. Simulation results show that this scheme reduces the transmission delay of the communication overhead and the computational latency of encryption and decryption, and improves the security of the group key compared with the benchmark scheme.

Published
2020
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32. Motion Estimation for Video Coding Based on Subspace Pursuit

Author

Shen, Yanfei, Li, Jintao, Zhu, Zhenmin, Zhang, Yongdong, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Huet, Benoit, editor, Ngo, Chong-Wah, editor, Tang, Jinhui, editor, Zhou, Zhi-Hua, editor, Hauptmann, Alexander G., editor, and Yan, Shuicheng, editor

Published
2013
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36. Design method of diffuse transmission free-form surface combined with collimation lens array

Author

Zhang Fumin, Wang Zhiyu, and Zhu Zhenmin

Subjects
010302 applied physics, Surface (mathematics), Materials science, business.industry, Global illumination, 01 natural sciences, Collimated light, 010309 optics, Optics, 0103 physical sciences, Diffuse transmission, Free form, Electrical and Electronic Engineering, business, Lens array, Diode
Abstract

Lighting-emitting diodes are widely applied in lighting systems, and diffusers are commonly used in systems for indirect illumination. In this paper, a design method of diffuse transmission free-form surface combined with collimation lens array is proposed. Based on the Lambertian characteristics of lighting-emitting diodes and the principle of collimation lenses, a mathematical model of diffuser with ideal diffuse transmission free-form surface is established. We propose a method of the preset collimation surface to connect the free-form surface and the collimation lens array, and derive the nonlinear algebraic equation of the diffuse transmission free-form surface according to the connection effect of the preset collimation surface. Then, solving the equation numerically by MATLAB, the profile of the diffuse transmission free-form surface is obtained. Finally, the non-sequential ray tracing software TracePro is used to simulate the irradiance distribution of the target plane. The results show better uniformity and higher efficiency comparing with the lighting system using diffuse transmission free-form surface alone and the traditional diffuse transmission lighting system.

Published
2020

40. Design method of double freeform surface lens with diffuse reflection

Author

Zhu Zhenmin, Xin Xu, Jie Yuan, and Bo Peng

Subjects
010302 applied physics, Surface (mathematics), Materials science, business.industry, 01 natural sciences, law.invention, 010309 optics, Lens (optics), Optics, law, 0103 physical sciences, Diffuse reflection, Electrical and Electronic Engineering, business
Abstract

The design method of a double freeform surface lens is being widely applied in non-imaging optical systems. In this paper, a diffuse reflection freeform surface is introduced into the design of a double freeform surface lens. Different from the universal double freeform surface lens, this double freeform surface lens is divided into a small-angle freeform surface and a large-angle diffuse reflection freeform surface. The small-angle freeform surface firstly limits and forms the lighting area. Then, the large-angle freeform surface is designed to improve the efficiency of lighting the area. And this front light diffuse reflection effectively avoids the influence of light source projection onto the lighting effects. Based on this design method, the double freeform surface lens is obtained. The results show that the efficiency of a circular lighting area reaches 81% and the uniformity of the irradiance distribution reaches 91%. And this design is also suitable for forming different shapes of lighting areas while maintaining a better lighting effect.

Published
2019

41. Design of a combined lens for rectangular illumination

Author

Bo Peng, Xin Xu, Jie Yuan, and Zhu Zhenmin

Subjects
Physics, Field (physics), business.industry, 0211 other engineering and technologies, Physics::Optics, 02 engineering and technology, 01 natural sciences, Refraction, law.invention, 010309 optics, Lens (optics), LED lamp, Optics, law, 021105 building & construction, 0103 physical sciences, Electrical and Electronic Engineering, business
Abstract

Rectangular illumination has found extensive application in the field of LED lighting. In this paper, a design method for a combined lens has used the two characteristics of refraction and diffuse reflection for rectangular illumination. The combined lens is composed of a cutting lens and a pedestal. We determined the cutting lens through the shape of the target plane and then applied diffuse reflection material to the partial surface of the pedestal. The diffuse reflection material is used to improve the lighting efficiency of the target plane. The surface of the pedestal is obtained by lofting from the contour of the cutting lens to the contour of plane where the light source is placed. Based on this method, the combined lens is designed for rectangular illumination. The result shows that the performance of the target plane meets the requirements of rectangular lighting. The uniformity is about 88% and the lighting efficiency is improved to 75%.

Published
2018

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