This paper proposes a digital watermarking algorithm of combining the chaos with the wavelet transform. Firstly, three-color separation is performed over dual carrier images; secondly, chaotic scrambling is carried out over RGB components of the watermark using different secret keys, followed by wavelet transform; then, corresponding components are embedded, allowing for improved watermark security, as different secret keys are used for different components; furthermore, according to the property of human vision system being variably sensitive to different regions of the wavelet transformed image, the watermark is embedded into medium and low frequency domain of wavelet transform, so as to balance transparency and robustness of the watermark. Experimental results show that this watermarking algorithm has kept image quality relatively well with high security, and exhibited good robustness to such attacks as Gaussian and compression etc.
The sensing principle of FBG packaged was developed, and packaging technology for fiber Bragg gratings (FBGs) and
the embedding technique were studied. A scheme of packaging technology using the red copper slice for FBGs was
presented, and experimental results indicate that the strain sensitivity coefficient of FBG packaged is nearly the same as
that of the bare FBG, and that the FBG packaged can measure the 1με change, and that the temperature sensitivity
coefficient of FBG packaged is 2.97 times as much as that of the bare FBG, and that the packaging structure using red
copper slice improves the temperature resolution of demodulation equipment for FBG sensors, and that the FBG
packaged sensors can measure the 0.03°C change.
The novel FBG temperature sensor eliminating lateral strain cross-sensitivity was present and theoretically analyzed. The
temperature sensor characteristic of the FBG based on the method for eliminating lateral strain was researched from
room temperature to 190°C, and the FBG was pressed by lateral force during rising temperature. The lateral force
resulted in the birefringence of the FBG, and the FBG exited two different reflective spectra meeting with the Bragg
condition. The change spacing of the peak value between two reflective spectra is used to eliminate lateral strain crosssensitivity
to temperature, and amend the temperature sensitivity coefficient and the change temperature value.