Laser & Optoelectronics Progress, Volume. 59, Issue 14, 1415008(2022)

Depth-Adaptive Dynamic Neural Networks: A Survey

Yi Sun, Jian Li*, Xin Xu**, and Yuru Wang
Author Affiliations
  • College of Intelligence Science and Technology, National University of Defense Technology, Changsha 410000, Hunan , China
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    Figures & Tables(13)
    Depth adaptive neural networks for automatically adjusting inference depth based on the input complexity. (a) Network structure for processing simple input; (b) network structure for processing complex input
    Typical structures of depth-adaptive neural networks. (a) Multi-exit neural network; (b) skip-connection network
    Information exchange scheme of output module
    Network structure MSDNet based on multi-scale down sampling[34]
    Classification accuracy of MSDNet and Ensemble-ResNets on ImageNet dataset[34]
    Basic structure of Gate Module
    Samples with different complexity. (a) Samples with relatively simple texture and background; (b) complex samples
    Shared parameters θ receives conflict gradients from different exits. (a) Conflicted gradients have negative cosine similarity value; (b) level of gradient conflict in the training stage
    Network structure with dense connection
    • Table 1. Overview about the depth-adaptive neural networks

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      Table 1. Overview about the depth-adaptive neural networks

      MethodNetwork structure

      Depth-adaptive policy

      (input-complexity estimation)

      Training method
      Multi-exit

      Independent output branches33-36

      Additive/geometric ensemble37-38

      Multi-scale feature fusion39

      Multi-scale receptive field3438

      Confidence-based early exiting33-3740-42

      Mutual information estimation early exiting43-44

      Learning policy networks for early exiting45-47

      Weighted gradient descent283348

      Knowledge distillation49-51

      Gradient adjustment3852

      Skip-style

      Centralized gate module53

      Distributed gate module54-56

      Randomly block dropout57-58

      Skipping non-linear blocks53-58

      Sparse regularization56

      Reinforcement-learning based53

    • Table 2. Performance comparison of different information fusion approaches on CIFAR100 dataset

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      Table 2. Performance comparison of different information fusion approaches on CIFAR100 dataset

      MethodExit-1Exit-2Exit-3Exit-4
      Baseline66.7770.3171.9373.0
      Additive-ensemble66.0470.7072.4973.23
      Geometric-ensemble63.9170.3572.6773.01
      Multi-scale feature fusion66.6070.5372.7573.05
    • Table 3. Performance comparison of multi-exit networks trained by knowledge distillation

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      Table 3. Performance comparison of multi-exit networks trained by knowledge distillation

      MethodExit-1Exit-2Exit-3Exit-4Exit-5
      MSDNet3479.2586.4689.1589.8390.75
      IMPR3880.1587.8990.5291.3391.74
      DBT5080.8086.9288.8289.1589.73
      H-DBT4983.0687.1290.8591.992.04
    • Table 4. Performance comparison of multi-exit networks after using different gradient adjustment approaches on ImageNet dataset

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      Table 4. Performance comparison of multi-exit networks after using different gradient adjustment approaches on ImageNet dataset

      MethodExit-1Exit-2Exit-3Exit-4Exit-5
      MSDNet3458.4865.9668.6669.4871.03
      IMPR-GE3857.7565.5469.2470.2771.89
      PCgrad+GE5257.6264.8768.9371.0572.45
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    Yi Sun, Jian Li, Xin Xu, Yuru Wang. Depth-Adaptive Dynamic Neural Networks: A Survey[J]. Laser & Optoelectronics Progress, 2022, 59(14): 1415008

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    Paper Information

    Category: Machine Vision

    Received: Apr. 12, 2022

    Accepted: May. 23, 2022

    Published Online: Jul. 1, 2022

    The Author Email: Li Jian (lijian@nudt.edu.cn), Xu Xin (xinxu@nudt.edu.cn)

    DOI:10.3788/LOP202259.1415008

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