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16 results on '"Fu, M.S."'

9. Anomalous dielectric behaviour at the monoclinic to tetragonal phase transition in La(Nb0.9V0.1)O4

Author

Zhou, D., Guo, H.-H., Fu, M.S., Yao, X., Lin, H., Liu, W., Pang, L.-X., singh, C., Trukhanov, S., Trukhanov, A., and Reaney, I.M.

Abstract

La(Nb0.9V0.1)O4 has been shown by in-situ Raman spectra and X-ray diffraction to undergo a ferroelastic phase transition from monoclinic fergusonite to tetragonal scheelite (TM-T) at 350 oC, accompanied by 3.55% spontaneous strain and an abrupt change in thermal expansion coefficient (αL) from +15.5 ppm/oC to +11.4 ppm/oC. Assuming a linear relation between polarizability and temperature, an anomalous decrease in relative permittivity (εr) at TM-T is predicted from the Clausius–Mosotti relation and Shannon’s additive rule. Such an anomalous decrease in εr at a phase transition has not previously been observed in ferroic and linear dielectrics and may aid in the design of novel microwave dielectric composites.

Published
2021

13. Joint visual cryptography and watermarking

Author

Fu, M.S., Au, O.C., Fu, M.S., and Au, O.C.

Abstract

In this paper, we discuss how to use watermarking technique for visual cryptography. Both halftone watermarking and visual cryptography involve a hidden secret image. However, their concepts are different. For visual cryptography, a set of share binary images is used to protect the content of the hidden image. The hidden image can only be revealed when enough share images are obtained. For watermarking, the hidden image is usually embedded in a single halftone image while preserving the quality of the watermarked halftone image. In this paper, we proposed a Joint Visual-cryptography and watermarking (JVW) algorithm that has the merits of both visual cryptography and watermarking.

Published
2004

14. A Symmetric Key Watermark for Halftone Images

Author

Au, O.C., Fu, M.S., Au, O.C., and Fu, M.S.

Abstract

In many printer and publishing applications, it is desirable to embed data in halftone images for copyright control and authentication purposes. While intentional attacks on printed matters may not be likely, unintentional attacks such as cropping and distortion due to dirt or human writing/marking are likely. In this paper, we proposed a novel halftone image watermarking method called Watermarking Error Diffusion (WED) to embed a watermark in the parity domain of halftone images with symmetric key during halftoning while introducing minimal distortion.

Published
2003

16. Structure and microwave dielectric characteristics of Ca1−x Nd2x/3TiO3 ceramics

Author

Fu, M.S., Liu, X.Q., and Chen, X.M.

Subjects
*DIELECTRICS, *CERAMICS, *MICROWAVES, *PEROVSKITE, *OXIDE minerals
Abstract

Abstract: Dense Ca1−x Nd2x/3TiO3 ceramics with x =0.30, 0.39 and 0.48 were prepared by a solid-state reaction process, and the crystal structure was determined together with the microwave dielectric characterization. The tilted orthorhombic perovskite structure in space group Pnma was refined in the present ceramics where a minor amount of TiO2 was detected as the secondary phase. The microwave dielectric characteristics were strongly affected by the Nd3+ concentration and the processing conditions. The best combination of microwave dielectric characteristics was obtained for the as-sintered samples with x =0.39: ɛ r =103, Qf=15340GHz and τ f =247ppm/°C. Especially, a sharp decrease of Qf was observed for samples with x =0.39 after annealing in oxygen. Both the dielectric constant and temperature coefficient of resonant frequency of the present ceramics were dependent on the bond valence of the octahedral site. Dielectric loss was significantly affected by the lattice defects and the disordered charge distribution. [Copyright &y& Elsevier]

Published
2008
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