Default hparams for Revnet.

def revnet_base():
  """Default hparams for Revnet."""
  hparams = common_hparams.basic_params1()
  hparams.add_hparam('num_channels', [64, 128, 256, 416])
  hparams.add_hparam('num_layers_per_block', [1, 1, 10, 1])
  hparams.add_hparam('bottleneck', True)
  hparams.add_hparam('first_batch_norm', [False, True, True, True])
  hparams.add_hparam('init_stride', 2)
  hparams.add_hparam('init_kernel_size', 7)
  hparams.add_hparam('init_maxpool', True)
  hparams.add_hparam('strides', [1, 2, 2, 2])
  hparams.add_hparam('num_channels_init_block', 64)
  hparams.add_hparam('dim', '2d')

  # Variable init
  hparams.initializer = 'normal_unit_scaling'
  hparams.initializer_gain = 2.

  # Optimization
  hparams.optimizer = 'Momentum'
  hparams.optimizer_momentum_momentum = 0.9
  hparams.optimizer_momentum_nesterov = True
  hparams.weight_decay = 1e-4
  hparams.clip_grad_norm = 0.0
  # (base_lr=0.1) * (batch_size=128*8 (on TPU, or 8 GPUs)=1024) / (256.)
  hparams.learning_rate = 0.4
  hparams.learning_rate_decay_scheme = 'cosine'
  # For image_imagenet224, 120k training steps, which effectively makes this a
  # cosine decay (i.e. no cycles).
  hparams.learning_rate_cosine_cycle_steps = 120000

  # Can run with a batch size of 128 with Problem ImageImagenet224
  hparams.batch_size = 128
  return hparams