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Pin Gong,Minxuan Ni,Hao Chai,Feida Chen,Xiaobin Tang 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.3
With a highly functional methyl vinyl silicone rubber (VMQ) matrix and filler materials of B4C, PbO, andbenzophenone (BP) and through powder surface modification, silicone rubber mixing, and vulcanizedmolding, a flexible radiation shielding and resistant composite was prepared in the study. The dispersionproperty of the powder in the matrix filler was improved by powder surface modification. BP was addedinto the matrix to enhance the radiation resistance performance of the composites. After irradiation, thetensile strength, elongation, and tear strength of the composites decreased, while the Shore hardness ofthe composites and the crosslinking density of the VMQ matrix increased. Moreover, the compositeswith BP showed better mechanical properties and smaller crosslinking density than those without BPafter irradiation. The initial degradation temperatures of the composites containing BP before and afterirradiation were 323.6 C and 335.3 C, respectively. The transmission of neutrons for a 2-mm thicksample was only 0.12 for an AmeBe neutron source. The transmission of g-rays with energies of 0.662,1.173, and 1.332 MeV for 2-cm thick samples were 0.7, 0.782, and 0.795, respectively
Build-in Wiretap Channel I with Feedback and LDPC Codes
Wen, Hong,Gong, Guang,Ho, Pin-Han The Korea Institute of Information and Commucation 2009 Journal of communications and networks Vol.11 No.6
A wiretap channel I is one of the channel models that was proved to achieve unconditional security. However, it has been an open problem in realizing such a channel model in a practical network environment. The paper is committed to solve the open problem by introducing a novel approach for building wiretap channel I in which the eavesdropper sees a binary symmetric channel (BSC) with error probability p while themain channel is error free. By taking advantage of the feedback and low density parity check (LDPC) codes, our scheme adds randomness to the feedback signals from the destination for keeping an eavesdropper ignorant; on the other hand, redundancy is added and encoded by the LDPC codes such that a legitimate receiver can correctly receive and decode the signals. With the proposed approach, unconditionallysecure communication can be achieved through interactive communications, in which the legitimate partner can realize the secret information transmission without a pre-shared secret key even if the eavesdropper has better channel from the beginning.
Build-in Wiretap Channel I with Feedback and LDPC Codes
Hong Wen,Guang Gong,Pin-Han Ho 한국통신학회 2009 Journal of communications and networks Vol.11 No.6
A wiretap channel I is one of the channel models that was proved to achieve unconditional security. However, it has been an open problem in realizing such a channel model in a practical network environment. The paper is committed to solve the open problem by introducing a novel approach for building wiretap channel I in which the eavesdropper sees a binary symmetric channel (BSC) with error probability p while themain channel is error free. By taking advantage of the feedback and low density parity check (LDPC) codes, our scheme adds randomness to the feedback signals from the destination for keeping an eavesdropper ignorant; on the other hand, redundancy is added and encoded by the LDPC codes such that a legitimate receiver can correctly receive and decode the signals. With the proposed approach, unconditionallysecure communication can be achieved through interactive communications, in which the legitimate partner can realize the secret information transmission without a pre-shared secret key even if the eavesdropper has better channel from the beginning.
Low-noise reconstruction method for coded-aperture gamma camera based on multi-layer perceptron
Rui Zhang,Xiaobin Tang,Pin Gong,Peng Wang,Cheng zhou,Xiaoxiang Zhu,Dajian Liang,Zeyu Wang 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.10
Accurate localization of radioactive materials is crucial in homeland security and radiological emergencies. Coded-aperture gamma camera is an interesting solution for such applications and can be developed into portable real-time imaging devices. However, traditional reconstruction methods cannot effectively deal with signal-independent noise, thereby hindering low-noise real-time imaging. In this study, a novel reconstruction method with excellent noise-suppression capability based on a multi-layer perceptron (MLP) is proposed. A coded-aperture gamma camera based on pixel detector and coded-aperture mask was constructed, and the process of radioactive source imaging was simulated. Results showed that the MLP method performs better in noise suppression than the traditional correlation analysis method. When the Co-57 source with an activity of 1 MBq was at 289 different positions within the field of view which correspond to 289 different pixels in the reconstructed image, the average contrast-to-noise ratio (CNR) obtained by the MLP method was 21.82, whereas that obtained by the correlation analysis method was 5.85. The variance in CNR of the MLP method is larger than that of correlation analysis, which means the MLP method has some instability in certain conditions.