The problem of tag completion is to learn the missing tags of an image. In this paper, we propose to learn a tag scoring vector for each image by local linear learning. A local linear function is used in the neighborhood of each image to predict the tag scoring vectors of its neighboring images. We construct a unified objective function for the learning of both tag scoring vectors and local linear function parameters. In the objective, we impose the learned tag scoring vectors to be consistent with the known associations to the tags of each image, and also minimize the prediction error of each local linear function, while reducing the complexity of each local function. The objective function is optimized by an alternate optimization strategy and gradient descent methods in an iterative algorithm. We compare the proposed algorithm against different state-of-the-art tag completion methods, and the results show its advantages.

We experimentally study the resonance fluorescence from an excited two-level atom when the atomic upper level is coupled by a nonresonant field to a higher-lying state in a rubidium atomic beam. The heights, widths and positions of the fluorescence peaks can be controlled by modifying the detuning of the auxiliary field. We explain the observed spectrum with the transition properties of the dressed states generated by the coupling of the two laser fields. We also attribute the line narrowing to the effects of Spontaneously Generated Coherence between the close-lying levels in the dressed state picture generated by the auxiliary field. And the corresponding spectrum can be viewed as the evidence of Spontaneously Generated Coherence. The experimental results agree well with calculations based on the density-matrix equations.

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In order to improve the electrochemical performance of FePO 4, the method of Cr 3+ ion-doped FePO 4 was proposed in this paper. FePO 4 and doped Fe 1-x Cr x PO 4 (x = 0.02,0.04,0.06 and 0.08) were prepared by homogeneous co-precipitation followed by spray drying method, and then the samples were sintered at different temperatures (380°C, 460°C, 550°C and 650°C). Physical-chemical properties were characterized by using thermogravimetric analysis (TG), X-ray diffraction (XRD) and scanning electron microscope (SEM); electrochemical behavior of the samples were analyzed using charge–discharge test, electrochemical impedance spectroscopy (EIS). The results indicated that the Cr 3+ doping can effectively improve the electrochemical performance of FePO 4. Fe 0.96 Cr 0.04 PO 4 sintered at 460°C showed the highest specific capacity of 109.7 mAh/g for the 1st cycle at 0.05 C. In addition, the doping mechanism for FePO 4 was discussed in this paper.