176 research outputs found
Shear Creep Simulation of Structural Plane of Rock Mass Based on Discontinuous Deformation Analysis
Numerical simulations of the creep characteristics of the structural plane of rock mass are very useful. However, most existing simulation methods are based on continuum mechanics and hence are unsuitable in the case of large displacements and deformations. The discontinuous deformation analysis method proposed by Genhua is a discrete one and has a significant advantage when simulating the contacting problem of blocks. In this study, we combined the viscoelastic rheological model of Burgers with the discontinuous deformation analysis (DDA) method. We also derived the recurrence formula for the creep deformation increment with the time step during numerical simulations. Based on the minimum potential energy principle, the general equilibrium equation was derived, and the shear creep deformation in the structural plane was considered. A numerical program was also developed and its effectiveness was confirmed based on the curves obtained by the creep test of the structural plane of a rock mass under different stress levels. Finally, the program was used to analyze the mechanism responsible for the creep features of the structural plane in the case of the toppling deformation of the rock slope. The results showed that the extended DDA method is an effective one
Lookaround Optimizer: steps around, 1 step average
Weight Average (WA) is an active research topic due to its simplicity in
ensembling deep networks and the effectiveness in promoting generalization.
Existing weight average approaches, however, are often carried out along only
one training trajectory in a post-hoc manner (i.e., the weights are averaged
after the entire training process is finished), which significantly degrades
the diversity between networks and thus impairs the effectiveness in
ensembling. In this paper, inspired by weight average, we propose Lookaround, a
straightforward yet effective SGD-based optimizer leading to flatter minima
with better generalization. Specifically, Lookaround iterates two steps during
the whole training period: the around step and the average step. In each
iteration, 1) the around step starts from a common point and trains multiple
networks simultaneously, each on transformed data by a different data
augmentation, and 2) the average step averages these trained networks to get
the averaged network, which serves as the starting point for the next
iteration. The around step improves the functionality diversity while the
average step guarantees the weight locality of these networks during the whole
training, which is essential for WA to work. We theoretically explain the
superiority of Lookaround by convergence analysis, and make extensive
experiments to evaluate Lookaround on popular benchmarks including CIFAR and
ImageNet with both CNNs and ViTs, demonstrating clear superiority over
state-of-the-arts. Our code is available at
https://github.com/Ardcy/Lookaround.Comment: 18 pages, 9 figure
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