OVSNet : Towards One-Pass Real-Time Video Object Segmentation

Video object segmentation aims at accurately segmenting the target object regions across consecutive frames. It is technically challenging for coping with complicated factors (e.g., shape deformations, occlusion and out of the lens). Recent approaches have largely solved them by using backforth re-identification and bi-directional mask propagation. However, their methods are extremely slow and only support offline inference, which in principle cannot be applied in real time. Motivated by this observation, we propose a efficient detection-based paradigm for video object segmentation. We propose an unified One-Pass Video Segmentation framework (OVS-Net) for modeling spatial-temporal representation in a unified pipeline, which seamlessly integrates object detection, object segmentation, and object re-identification. The proposed framework lends itself to one-pass inference that effectively and efficiently performs video object segmentation. Moreover, we propose a maskguided attention module for modeling the multi-scale object boundary and multi-level feature fusion. Experiments on the challenging DAVIS 2017 demonstrate the effectiveness of the proposed framework with comparable performance to the state-of-the-art, and the great efficiency about 11.5 FPS towards pioneering real-time work to our knowledge, more than 5 times faster than other state-of-the-art methods.Comment: 10 pages, 6 figure

Capacity of a simultaneous quantum secure direct communication scheme between the central party and other M parties

We analyze the capacity of a simultaneous quantum secure direct communication scheme between the central party and other $M$ parties via $M+1$-particle GHZ states and swapping quantum entanglement. It is shown that the encoding scheme should be secret if other $M$ parties wants to transmit $M+1$ bit classical messages to the center party secretly. However when the encoding scheme is announced publicly, we prove that the capacity of the scheme in transmitting the secret messages is 2 bits, no matter how big $M$ is.Comment: 3 page

Vertical Distribution of C_3-hydrocarbons in the Stratosphere of Titan

Motivated by the recent detection of propene (C_3H_6) in the atmosphere of Titan, we use a one-dimensional Titan photochemical model with an updated eddy diffusion profile to systematically study the vertical profiles of the stable species in the C_3-hydrocarbon family. We find that the stratospheric volume mixing ratio of propene (C_3H_6) peaks at 150 km with a value of 5 × 10^(−9), which is in good agreement with recent observations by the Composite Infrared Spectrometer on the Cassini spacecraft. Another important species that is currently missing from the hydrocarbon family in Titan's stratosphere is allene (CH_2CCH_2), an isomer of methylacetylene (CH_3C_2H). We predict that its mixing ratio in the stratosphere is about 10^(−9), which is on the margin of the detection limit. CH_2CCH_2 and CH_3C_2H equilibrate at a constant ratio in the stratosphere by hydrogen-exchanging reactions. Thus, by precisely measuring the ratio of CH_2CCH_2 to CH_3C_2H, the abundance of atomic hydrogen in the atmosphere can be inferred. No direct yield for the production of cyclopropane (c-C_3H_6) is available. From the discharge experiments of Navarro-González & Ramírez, the abundance of cyclopropane is estimated to be 100 times less than that of C_3H_6