37,077 research outputs found
Comparisons and Applications of Four Independent Numerical Approaches for Linear Gyrokinetic Drift Modes
To help reveal the complete picture of linear kinetic drift modes, four
independent numerical approaches, based on integral equation, Euler initial
value simulation, Euler matrix eigenvalue solution and Lagrangian particle
simulation, respectively, are used to solve the linear gyrokinetic
electrostatic drift modes equation in Z-pinch with slab simplification and in
tokamak with ballooning space coordinate. We identify that these approaches can
yield the same solution with the difference smaller than 1\%, and the
discrepancies mainly come from the numerical convergence, which is the first
detailed benchmark of four independent numerical approaches for gyrokinetic
linear drift modes. Using these approaches, we find that the entropy mode and
interchange mode are on the same branch in Z-pinch, and the entropy mode can
have both electron and ion branches. And, at strong gradient, more than one
eigenstate of the ion temperature gradient mode (ITG) can be unstable and the
most unstable one can be on non-ground eigenstates. The propagation of ITGs
from ion to electron diamagnetic direction at strong gradient is also observed,
which implies that the propagation direction is not a decisive criterion for
the experimental diagnosis of turbulent mode at the edge plasmas.Comment: 12 pages, 10 figures, accept by Physics of Plasma
Task-Oriented Multi-User Semantic Communications for VQA
Semantic communications focus on the transmission of semantic features. In this letter, we consider a task-oriented multi-user semantic communication system for multimodal data transmission. Particularly, partial users transmit images while the others transmit texts to inquiry the information about the images. To exploit the correlation among the multimodal data from multiple users, we propose a deep neural network enabled semantic communication system, named MU-DeepSC, to execute the visual question answering (VQA) task as an example. Specifically, the transceiver for MU-DeepSC is designed and optimized jointly to capture the features from the correlated multimodal data for task-oriented transmission. Simulation results demonstrate that the proposed MU-DeepSC is more robust to channel variations than the traditional communication systems, especially in the low signal-to-noise (SNR) regime
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