1,456 research outputs found
Channel Model in Urban Environment for Unmanned Aerial Vehicle Communications
In order to develop and analyze reliable communications links for unmanned
aerial vehicles (UAVs), accurate models for the propagation channel are
required. The radio channel properties in the urban scenario are different from
those in the suburb scenario and open area due to so many scattering paths from
office buildings, especially when the UAV flies in the low altitude. We took
some measurement campaigns on the campus of Tsinghua University with crowded
apartments and office buildings. Based on the measurement result we extract the
main parameters of pathloss model, and propose a simplified Saleh-Valenzuela
(SV) model with specific parameters. The typical scene of central lawn is
compared with the office buildings in the analysis of K-factor and
root-mean-square (RMS) delay spread.Comment: to prepare in European Conference on Antennas and Propagetion
(EUCAP), 201
Robust Pose Transfer with Dynamic Details using Neural Video Rendering
Pose transfer of human videos aims to generate a high fidelity video of a
target person imitating actions of a source person. A few studies have made
great progress either through image translation with deep latent features or
neural rendering with explicit 3D features. However, both of them rely on large
amounts of training data to generate realistic results, and the performance
degrades on more accessible internet videos due to insufficient training
frames. In this paper, we demonstrate that the dynamic details can be preserved
even trained from short monocular videos. Overall, we propose a neural video
rendering framework coupled with an image-translation-based dynamic details
generation network (D2G-Net), which fully utilizes both the stability of
explicit 3D features and the capacity of learning components. To be specific, a
novel texture representation is presented to encode both the static and
pose-varying appearance characteristics, which is then mapped to the image
space and rendered as a detail-rich frame in the neural rendering stage.
Moreover, we introduce a concise temporal loss in the training stage to
suppress the detail flickering that is made more visible due to high-quality
dynamic details generated by our method. Through extensive comparisons, we
demonstrate that our neural human video renderer is capable of achieving both
clearer dynamic details and more robust performance even on accessible short
videos with only 2k - 4k frames.Comment: Video link: https://www.bilibili.com/video/BV1y64y1C7ge
Microstructure evolution and electrochemical properties of TiO 2 /Ti-35Nb-2Ta-3Zr micro/nano-composites fabricated by friction stir processing
Forming stable anti-corrosion surface layer and homogenized microstructure on the surface of material has become a major challenge in developing biomedical β titanium alloy. In the study, TiO 2 /Ti-35Nb-2Ta-3Zr anti-corrosion micro/nano-composites with different amount of TiO 2 particles were successfully fabricated by one-pass friction stir processing (FSP). The composition, microstructure and electrochemical properties of the material are characterized systematically. In particular, compact passive oxide films formed on surface of the material after electrochemical corrosion are elaborated from constituent, thickness and structural characteristics. Furthermore, the relationship between various FSP parameters, microstructure presented and corresponding corrosion resistance has been discussed in detail. The results show that TiO 2 /Ti-35Nb-2Ta-3Zr micro/nano-composite layers possess massive uniform β grains with homogeneous dispersive oxygen on the surface. Nanocrystallines surrounded by amorphous phases and α″ martensite accompanied with dislocations are discovered. TiO 2 /Ti-35Nb-2Ta-3Zr micro/nano-composite layers present outstanding corrosion resistance. More TiO 2 added and higher rotation speed promotes the optimization in corrosion resistance forming more compact passive films. The study displays the potential of a new micro/nano-composite with outstanding surface microstructure and corrosion resistance that serves better as a biomedical implant. © 2019 Elsevier Lt
- …