Saliency-guided video classification via adaptively weighted learning

Video classification is productive in many practical applications, and the recent deep learning has greatly improved its accuracy. However, existing works often model video frames indiscriminately, but from the view of motion, video frames can be decomposed into salient and non-salient areas naturally. Salient and non-salient areas should be modeled with different networks, for the former present both appearance and motion information, and the latter present static background information. To address this problem, in this paper, video saliency is predicted by optical flow without supervision firstly. Then two streams of 3D CNN are trained individually for raw frames and optical flow on salient areas, and another 2D CNN is trained for raw frames on non-salient areas. For the reason that these three streams play different roles for each class, the weights of each stream are adaptively learned for each class. Experimental results show that saliency-guided modeling and adaptively weighted learning can reinforce each other, and we achieve the state-of-the-art results.Comment: 6 pages, 1 figure, accepted by ICME 201

Bimodal waveguide interferometer RI sensor fabricated on low-cost polymer platform

A refractive index sensor based on bimodal waveguide interferometer is demonstrated on the low-cost polymer platform for the first time. Different from conventional interferometers which make use of the interference between the light from two arms, bimodal waveguide interferometers utilize the interference between the two different internal modes in the waveguide. Since the utilized first higher mode has a wide evanescent tail which interacts with the external environment, the interferometer can reach a high sensitivity. Instead of vertical bimodal structure which is normally employed, the lateral bimodal waveguide is adopted in order to simplify the fabrication process. A unique offset between the centers of single mode waveguide and bimodal waveguide is designed to excite the two different modes with equal power which contributes to the maximum fringe visibility. The bimodal waveguide interferometer is finally fabricated on optical polymer (Ormocore) which is transparent at both infrared and visible wavelengths. It is fabricated using the UV-based soft imprint technique which is simple and reproductive. The bulk sensitivity of fabricated interferometer sensor with a 5 mm sensing length is characterized using different mass concentration sodium chloride solutions. The sensitivity is obtained as 316 pi rad/RIU and the extinction ratio can reach 18 dB