An optical temperature sensor based on infrared-to-visible upconversion emission in Er 3+ /Yb 3+ co-doped Bi3TiNb O9 (BTN) ceramics is reported. The fluorescence intensity ratio of the green upconversion photoluminescence (UC-PL) around 524 nm and 545 nm depends on temperature. The operating temperature range and the maximum sensitivity of Er 3+ /Yb 3+ co-doped Bi3TiNbO9 ceramics are 123-693 K and 0.0032 K −1 , respectively. BTN:Er 3+ /Yb 3+ ceramic has good thermal, physical and chemical stability, great UC-PL intensity and low cost fabrication. The results imply that Er 3+ /Yb 3+ co-doped Bi3TiNbO9 ceramic is promising for applications in wide-temperature-range sensors.

In this study, a disk-shaped step-down piezoelectric transformer that consists of Mg:LN single crystals operating in the extensional vibration mode was proposed, and its characteristics wre investigated. This paper proposed the PT using ring/dot electrode which had an outer diameter of 22 mm, a narrow annular gap circle of 1.0 mm and a thickness of 1.0 mm. The transformer was poled along the thickness direction. The top surface was covered by two ring-shaped electrodes separated by a narrow annular gap, and the regions covered by the outer and inner ring electrodes serve as the output and input parts of the transformer, respectively. The bottom surface was fully covered with a gold electrode. Moreover, according to the physical equivalent circuit model of the latest invented vibration mode, PT of Mg:LN single crystals were fabricated and characterized. Finally, we investigated the gain under different load resistances and input voltage.

Li et al. [Pattern Recognition 41 (2008) 3287 -- 329 proposed the constrained maximum variance mapping method. The CMVM is globally maximizing the distances between different manifolds. We find out that globally minimizing the distances between the same manifolds can have better recognition than CMVM method on the Yale face database, ORL face database and UMIST face database. Hence we propose to use an inverse constrained maximum variance mapping method (ICMVM) which can be seen as the inverse Laplacian Fisher discriminate criteria. Experiment results suggest that this new approach performs well.

Sapphire crystals grown by an improved Kyropoulos-like method were irradiated by gamma rays and electrons in this paper. Thermoluminescence (TL) and optical stimulated luminescence (OSL) properties of sapphire were studied. TL glow curves of sapphire were varied within the room temperature to 500°C at a heating rate of 10min•s-1. The OSL spectra wavelength covered were from 200nm to 700nm. There was a new peak at 220°C, which was produced by the irradiation of gamma rays and electrons. Two broad bands at 330nm and 410nm were found in the luminescence spectra, which were due to transitions of two charge states of an anion vacancy defect, corresponding to F+ and F color centers, respectively.

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