559 research outputs found
Atomically thin mononitrides SiN and GeN: new two-dimensional semiconducting materials
Low-dimensional Si-based semiconductors are unique materials that can both
match well with the Si-based electronics and satisfy the demand of
miniaturization in modern industry. Owing to the lack of such materials, many
researchers put their efforts into this field. In this work, employing a swarm
structure search method and density functional theory, we theoretically predict
two-dimensional atomically thin mononitrides SiN and GeN, both of which present
semiconducting nature. Furthermore study shows that SiN and GeN behave as
indirect band gap semiconductors with the gap of 1.75 and 1.20 eV,
respectively. The ab initio molecular dynamics calculation tells that both two
mononitrides can exist stably even at extremely high temperature of 2000 K.
Notably, electron mobilities are evaluated as 0.888x
and 0.413x for SiN and GeN, respectively. The present
work expands the family of low-dimensional Si-based semiconductors.Comment: arXiv admin note: text overlap with arXiv:1703.0389
Microdynamic analysis of ellipsoidal particle flow in a shear cell
This paper studies rheological properties of ellipsoidal particles in a model annular shear cell and compares them with the relevant parameters obtained for spherical particles under similar conditions using the discrete element method (DEM). Some important microdynamic variables such as velocity, coordination number, volume fraction and stress were considered. It was found that there are some differences between the spherical and ellipsoidal particles in terms of these properties. The feature was explained by the microscopic structures at particle scale such as those related to particle alignment and interparticle force
Look globally, age locally: Face aging with an attention mechanism
Face aging is of great importance for cross-age recognition and
entertainment-related applications. Recently, conditional generative
adversarial networks (cGANs) have achieved impressive results for face aging.
Existing cGANs-based methods usually require a pixel-wise loss to keep the
identity and background consistent. However, minimizing the pixel-wise loss
between the input and synthesized images likely resulting in a ghosted or
blurry face. To address this deficiency, this paper introduces an Attention
Conditional GANs (AcGANs) approach for face aging, which utilizes attention
mechanism to only alert the regions relevant to face aging. In doing so, the
synthesized face can well preserve the background information and personal
identity without using the pixel-wise loss, and the ghost artifacts and
blurriness can be significantly reduced. Based on the benchmarked dataset
Morph, both qualitative and quantitative experiment results demonstrate
superior performance over existing algorithms in terms of image quality,
personal identity, and age accuracy.Comment: arXiv admin note: text overlap with arXiv:1807.09251 by other author
Adaptive Control for Robotic Manipulators base on RBF Neural Network
An adaptive neural network controller is brought forward by the paper to solve trajectory tracking problems of robotic manipulators with uncertainties. The first scheme consists of a PD feedback and a dynamic compensator which is composed by neural network controller and variable structure controller. Neutral network controller is designed to adaptive learn and compensate the unknown uncertainties, variable structure controller is designed to eliminate approach errors of neutral network. The adaptive weight learning algorithm of neural network is designed to ensure online real-time adjustment, offline learning phase is not need; Global asymptotic stability (GAS) of system base on Lyapunov theory is analysised to ensure the convergence of the algorithm. The simulation results show that the kind of the control scheme is effective and has good robustness
Numerical analysis of effects of specularity coefficient and restitution coefficient on the hydrodynamics of particles in a rotating drum
Various simulations have been conducted to understand the macroscopic behavior of particles in the solid-gas flow in rotating drums in the past. In these studies, the no-slip wall boundary condition and fixed restitution coefficient between particles were usually adopted. The paper presents a numerical study of the gas-solid flow in a rotating drum to understand the effect of the specularity coefficient and restitution coefficient on the hydrodynamic behavior of particles in the segregation process. The volume fraction, granular pressure, granular temperature and their relationships are examined in detail. The boundary conditions of the no-slip and specularity coefficient of 1 are compared. In the simulations, two different sizes of particles with the same density are considered and the Eulerian–Eulerian multiphase model and the kinetic theory of granular flow (KTGF) are used. The results reveal that the hydrodynamical behavior of the particles in the rotating drum is affected by the boundary condition and restitution coefficient. In particular, the increase of specularity coefficient can increase the active region depth, angle repose, granular pressure for both small and large particles and granular temperature for large particles. With increasing restitution coefficient, the angle of repose decreases and granular pressure and temperature increase at the same volume fraction for both small and large particles
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