Face Anti-spoofing gains increased attentions recently in both academic and industrial fields. With the emergence of various CNN based solutions, the multi-modal(RGB, depth and IR) methods based CNN showed better performance than single modal classifiers. However, there is a need for improving the performance and reducing the complexity. Therefore, an extreme light network architecture(FeatherNet A/B) is proposed with a streaming module which fixes the weakness of Global Average Pooling and uses less parameters. Our single FeatherNet trained by depth image only, provides a higher baseline with 0.00168 ACER, 0.35M parameters and 83M FLOPS. Furthermore, a novel fusion procedure with "ensemble + cascade" structure is presented to satisfy the performance preferred use cases. Meanwhile, the MMFD dataset is collected to provide more attacks and diversity to gain better generalization. We use the fusion method in the Face Anti-spoofing Attack Detection Challenge@CVPR2019 and got the result of 0.0013(ACER), 0.999(TPR@FPR=10e-2), 0.998(TPR@FPR=10e-3) and 0.9814(TPR@FPR=10e-4).
We present a novel method to fabricate Zn-Al LDH (layered double hydroxides) film with 3D flower-like micro-and nanostructure on the aluminum foil. The wettability of the Zn-Al LDH film can be easily changed from superhydrophilic to superhydrophobic with a simple chemical modification. The as-prepared superhydrophobic surfaces have water CAs (contact angles) of 165±2 °. In order to estimate the drag reduction property of the surface with different adhesion properties, the experimental setup of the liquid/solid friction drag is proposed. The drag reduction ratio for the as-prepared superhydrophobic sample is 20~30% at low velocity. Bearing this in mind, we construct superhydrophobic surfaces that have numerous technical applications in drag reduction field.
One kind of ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate, is used to investigate the interaction between electrospray and corona discharge under positive and negative polarity. A high-speed camera, a digital camera, and an oscilloscope are applied to observe the shape of the meniscus and the jet, photograph the discharge plume, and observe the current waveform of discharge, respectively. The electrospray and discharge modes are studied under different flow rates and voltage conditions, and the experimental results show that there is only corona discharge with no jet at a low flow rate, while the intermittent jet or droplet emission is accompanied by corona discharge at a high flow rate, and no steady cone jet mode is obtained under all experimental conditions. The inevitability of corona discharge in the electrospray process of 1-ethyl-3-methylimidazolium tetrafluoroborate is analyzed from the viewpoint of electric field. Pulse discharge at low voltage depends on the oscillation of the meniscus. The frequency of pulse discharge can be changed indirectly by changing the voltage to control the oscillation of the meniscus. The influence of corona discharge and resultant space charge is not only on the electric field strength, but also on the shape, which is the reason why the liquid surface morphology is significantly different under positive and negative polarities.
The effect of an oscillating sheath on near-wall conductivity has been studied using a model of the incident electron motions with the characteristic parameters of the oscillating sheath quantified. The model predicted an increase in both the frequency of electron-wall collisions and the coefficient of secondary electron emission compared to the steady sheath regime. This effect indicates that near-wall conductivity is enhanced in the oscillating sheath regime.
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