22 research outputs found
Offline and Online Optical Flow Enhancement for Deep Video Compression
Video compression relies heavily on exploiting the temporal redundancy
between video frames, which is usually achieved by estimating and using the
motion information. The motion information is represented as optical flows in
most of the existing deep video compression networks. Indeed, these networks
often adopt pre-trained optical flow estimation networks for motion estimation.
The optical flows, however, may be less suitable for video compression due to
the following two factors. First, the optical flow estimation networks were
trained to perform inter-frame prediction as accurately as possible, but the
optical flows themselves may cost too many bits to encode. Second, the optical
flow estimation networks were trained on synthetic data, and may not generalize
well enough to real-world videos. We address the twofold limitations by
enhancing the optical flows in two stages: offline and online. In the offline
stage, we fine-tune a trained optical flow estimation network with the motion
information provided by a traditional (non-deep) video compression scheme, e.g.
H.266/VVC, as we believe the motion information of H.266/VVC achieves a better
rate-distortion trade-off. In the online stage, we further optimize the latent
features of the optical flows with a gradient descent-based algorithm for the
video to be compressed, so as to enhance the adaptivity of the optical flows.
We conduct experiments on a state-of-the-art deep video compression scheme,
DCVC. Experimental results demonstrate that the proposed offline and online
enhancement together achieves on average 12.8% bitrate saving on the tested
videos, without increasing the model or computational complexity of the decoder
side.Comment: 9 pages, 6 figure
Magnetic Tuning of Plasmonic Excitation of Gold Nanorods
By using gold nanorods as an example, we report the dynamic and reversible tuning of the plasmonic property of anisotropically shaped colloidal metal nanostructures by controlling their orientation using external magnetic fields. The magnetic orientational control enables instant and selective excitation of the plasmon modes of AuNRs through the manipulation of the field direction relative to the directions of incidence and polarization of light
Amorphous Cu-Mn hopcalite as novel Fenton-like catalyst for H2O2-activated degradation of tetracycline at circumneutral pH
Cu-Mn hopcalite, as a conventional catalyst showing potential in many chemical reactions, has been rarely researched for its applications in H2O2-activated Fenton-like reactions for the decomposition of refractory pollutants. In this work, an amorphous Cu-Mn hopcalite catalyst (CMO-200) was prepared by simple calcination of their precursors at 200 °C. At circumneutral pH, CMO-200 behaved more efficiently than several commercial manganese oxides, CuO, and Fe2O3, as well as its crystalline analogues in catalytic degradation of tetracycline (TC) with H2O2 as oxidant. The excellent performance can be kept without remarkable loss during its 6 cycles of reuse. Singlet oxygen, superoxide anion radical and hydroxyl radical were found to be active species for the degradation reaction. The amorphous structure and high contents of chemically adsorbed oxygen, Cu+ and Mn4+ species are speculated as the reasons for its high catalytic performance
Object recognition using rotation invariant local binary pattern of significant bit planes
Rough Structure of Electrodeposition as a Template for an Ultrarobust Self-Cleaning Surface
Superhydrophobic
surfaces with self-cleaning properties have been developed based on
roughness on the micro- and nanometer scales and low-energy surfaces.
However, such surfaces are fragile and stop functioning when exposed
to oil. Addressing these challenges, here we show an ultrarobust self-cleaning
surface fabricated by a process of metal electrodeposition of a rough
structure that is subsequently coated with fluorinated metal-oxide
nanoparticles. Scanning electron microscopy, Fourier-transform infrared
spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction
were employed to characterize the surfaces. The micro- and nanoscale
roughness jointly with the low surface energy imparted by the fluorinated
nanoparticles yielded surfaces with water contact angle of 164.1°
and a sliding angle of 3.2°. Most interestingly, the surface
exhibits fascinating mechanical stability after finger-wipe, knife-scratch,
sand abrasion, and sandpaper abrasion tests. It is found that the
surface with superamphiphobic properties has excellent repellency
toward common corrosive liquids and low-surface-energy substances.
Amazingly, the surface exhibited excellent self-cleaning ability and
remained intact even after its top layer was exposed to 50 abrasion
cycles with sandpaper and oil contamination. It is believed that this
simple, unique, and practical method can provide new approaches for
effectively solving the stability issue of superhydrophobic surfaces
and could extend to a variety of metallic materials
Magnetic Tuning of Plasmonic Excitation of Gold Nanorods
By using gold nanorods as an example,
we report the dynamic and
reversible tuning of the plasmonic property of anisotropically shaped
colloidal metal nanostructures by controlling their orientation using
external magnetic fields. The magnetic orientational control enables
instant and selective excitation of the plasmon modes of AuNRs through
the manipulation of the field direction relative to the directions
of incidence and polarization of light
Magnetic Tuning of Plasmonic Excitation of Gold Nanorods
By using gold nanorods as an example,
we report the dynamic and
reversible tuning of the plasmonic property of anisotropically shaped
colloidal metal nanostructures by controlling their orientation using
external magnetic fields. The magnetic orientational control enables
instant and selective excitation of the plasmon modes of AuNRs through
the manipulation of the field direction relative to the directions
of incidence and polarization of light