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Your search keyword '"He Yi"' showing total 128 results
Start Over Author "He Yi" Journal applied mechanics and materials
128 results on '"He Yi"'

1. Surface Chemical Modification and Characterization of Nano Fe2O3

Author

Shi Feng Huang, He Yi Ge, Xiu Zhi Zhang, Yan Liu, and Xin Cheng

Subjects
Contact angle, Thermogravimetric analysis, Materials science, Chemical engineering, Dispersity, Nano, Chemical modification, Nanoparticle, General Medicine, Fourier transform infrared spectroscopy, Hydrophile
Abstract

The surface of nanoFe2O3 was modified with silane coupling agent 3-(methacryloyloxy) propyltrimethoxysilane (KH-570) under acidic conditions in order to improve the dispersity of particles in organic polymer and to enhance the interfacial bonding with the matrix. Contact angle measurement, thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were adopted to characterize and analyze the unmodified and modified nanoFe2O3. Through TG curves, it was calculated that when the KH-570 content was 25%, the grafting rate of Fe2O3 reached a maximum value at 7.28%. The FT-IR and XRD results indicated that KH-570 successfully modified the nanoFe2O3 with its organic functional groups chemically bonded on the surface of nanoFe2O3 which contributed to prevent particles from conglomerating. The surface treatment of nanoFe2O3 had no significant effect on the nanoparticles crystalline form. Contact angle measurement investigated that the hydrophile of modified nanoFe2O3 was decreased.

Published
2013

2. A Novel Covert Communication Method Based on WCDMA

Author

He Yi Wu and Ai Qun Hu

Subjects
business.industry, Computer science, Data_CODINGANDINFORMATIONTHEORY, General Medicine, Computer security, computer.software_genre, OSI model, Base station, User equipment, Covert, Telecommunications link, Code (cryptography), business, computer, Computer network, Data transmission
Abstract

Covert communication can effectively improve the security of communication content, which has been widely used in wireless communication systems. Most approaches for covert communication are based on the principle of text-embedded in upper layer of the OSI model. In this paper, a novel covert communication scheme is proposed. This method takes advantage of scramble codes and message processing rules of the WCDMA system. It uses a downlink scramble code in the normal WCDMA uplink signal, so that the covert messages will not be received by the base station (BS) and the user equipment (UE). Simulation result shows that the proposed covert communication method has a low bit error rate (BER) performance, and will only make the signals of different business to a slightly lower data transmission rate.

Published
2013

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