请说说如何改进U-Net模型和DeepLabv3+模型用于提取雷达遥感水体信息的神经网络，并给出他们的模型代码

U-Net和DeepLabv3+是常用的用于图像分割的神经网络模型，可以用于提取雷达遥感水体信息。以下是我对这两种模型的改进建议：

1. U-Net模型改进：
- 使用更深的网络结构，例如加入更多的卷积层和池化层，以提高模型的表现力和泛化能力。
- 使用不同的损失函数，例如Focal Loss，Dice Loss等，以提高模型对边缘信息的准确度。
- 数据增强处理，例如旋转、翻转、缩放等，以增加数据的多样性，提高模型的鲁棒性。

以下是U-Net模型的代码：

import torch.nn as nn

class DoubleConv(nn.Module):
    def __init__(self, in_channels, out_channels):
        super(DoubleConv, self).__init__()
        self.conv = nn.Sequential(
            nn.Conv2d(in_channels, out_channels, 3, padding=1),
            nn.BatchNorm2d(out_channels),
            nn.ReLU(inplace=True),
            nn.Conv2d(out_channels, out_channels, 3, padding=1),
            nn.BatchNorm2d(out_channels),
            nn.ReLU(inplace=True)
        )

    def forward(self, x):
        return self.conv(x)

class UNet(nn.Module):
    def __init__(self, in_channels=1, out_channels=1, features=[64, 128, 256, 512]):
        super(UNet, self).__init__()
        self.ups = nn.ModuleList()
        self.downs = nn.ModuleList()
        self.pool = nn.MaxPool2d(kernel_size=2, stride=2)

        # Down part of U-Net
        for feature in features:
            self.downs.append(DoubleConv(in_channels, feature))
            in_channels = feature

        # Up part of U-Net
        for feature in reversed(features):
            self.ups.append(nn.ConvTranspose2d(feature*2, feature, kernel_size=2, stride=2))
            self.ups.append(DoubleConv(feature*2, feature))

        self.bottleneck = DoubleConv(features[-1], features[-1]*2)
        self.final_conv = nn.Conv2d(features[0], out_channels, kernel_size=1)

    def forward(self, x):
        skip_connections = []
        for down in self.downs:
            x = down(x)
            skip_connections.append(x)
            x = self.pool(x)

        x = self.bottleneck(x)
        skip_connections = skip_connections[::-1]

        for idx in range(0, len(self.ups), 2):
            x = self.ups[idx](x)
            skip_connection = skip_connections[idx//2]

            if x.shape != skip_connection.shape:
                x = TF.resize(x, size=skip_connection.shape[2:])

            concat_skip = torch.cat((skip_connection, x), dim=1)
            x = self.ups[idx+1](concat_skip)

        return self.final_conv(x)

2. DeepLabv3+模型改进：
- 加入空间金字塔池化模块，提高模型对不同尺度信息的捕获能力。
- 采用可变形卷积层，增加模型的感受野，提高模型对目标形状的适应性。
- 采用多尺度训练和测试，提高模型对不同尺度目标的检测能力。

以下是DeepLabv3+模型的代码：

import torch
import torch.nn as nn
import torch.nn.functional as F
from torch.utils import model_zoo

model_urls = {
    'resnet50': 'https://download.pytorch.org/models/resnet50-19c8e357.pth',
    'resnet101': 'https://download.pytorch.org/models/resnet101-5d3b4d8f.pth',
}

class ASPP(nn.Module):
    def __init__(self, in_channels, out_channels=256, rates=[6, 12, 18]):
        super(ASPP, self).__init__()
        self.conv1x1 = nn.Conv2d(in_channels, out_channels, kernel_size=1)
        self.atrous_conv1 = nn.Conv2d(in_channels, out_channels, kernel_size=3, padding=rates[0], dilation=rates[0])
        self.atrous_conv2 = nn.Conv2d(in_channels, out_channels, kernel_size=3, padding=rates[1], dilation=rates[1])
        self.atrous_conv3 = nn.Conv2d(in_channels, out_channels, kernel_size=3, padding=rates[2], dilation=rates[2])
        self.pool = nn.Sequential(
            nn.AdaptiveAvgPool2d(1),
            nn.Conv2d(in_channels, out_channels, kernel_size=1)
        )

        self.conv = nn.Conv2d(out_channels*5, out_channels, kernel_size=1)

    def forward(self, x):
        feature_map = self.conv1x1(x)
        atrous_1 = self.atrous_conv1(x)
        atrous_2 = self.atrous_conv2(x)
        atrous_3 = self.atrous_conv3(x)
        pool = F.interpolate(self.pool(x), size=feature_map.shape[2:], mode='bilinear', align_corners=True)

        x = torch.cat((feature_map, atrous_1, atrous_2, atrous_3, pool), dim=1)
        return self.conv(x)

class DeepLabv3Plus(nn.Module):
    def __init__(self, in_channels=3, out_channels=21, backbone='resnet50', pretrained=True):
        super(DeepLabv3Plus, self).__init__()
        if backbone == 'resnet50':
            resnet = models.resnet50(pretrained=pretrained)
            channels = 2048
        elif backbone == 'resnet101':
            resnet = models.resnet101(pretrained=pretrained)
            channels = 2048

        self.conv1 = resnet.conv1
        self.bn1 = resnet.bn1
        self.relu = resnet.relu
        self.maxpool = resnet.maxpool
        self.layer1 = resnet.layer1
        self.layer2 = resnet.layer2
        self.layer3 = resnet.layer3
        self.layer4 = resnet.layer4

        self.aspp = ASPP(channels)

        self.up_conv1 = nn.ConvTranspose2d(channels//2, channels//4, kernel_size=4, stride=2, padding=1)
        self.up_conv2 = nn.ConvTranspose2d(channels//4, channels//8, kernel_size=4, stride=2, padding=1)
        self.up_conv3 = nn.ConvTranspose2d(channels//8, channels//16, kernel_size=4, stride=2, padding=1)

        self.final_conv = nn.Conv2d(channels//16, out_channels, kernel_size=1)

    def forward(self, x):
        x_size = x.size()
        x = self.conv1(x)
        x = self.bn1(x)
        x = self.relu(x)
        x = self.maxpool(x)

        x = self.layer1(x)
        x = self.layer2(x)
        x = self.layer3(x)
        x = self.layer4(x)

        x = self.aspp(x)

        x = self.up_conv1(x)
        x = F.interpolate(x, size=self.layer3(x).size()[2:], mode='bilinear', align_corners=True)

        x = torch.cat((x, self.layer3(x)), dim=1)
        x = self.up_conv2(x)
        x = F.interpolate(x, size=self.layer2(x).size()[2:], mode='bilinear', align_corners=True)

        x = torch.cat((x, self.layer2(x)), dim=1)
        x = self.up_conv3(x)
        x = F.interpolate(x, size=self.layer1(x).size()[2:], mode='bilinear', align_corners=True)

        x = torch.cat((x, self.layer1(x)), dim=1)
        x = self.final_conv(x)
        x = F.interpolate(x, size=x_size[2:], mode='bilinear', align_corners=True)

        return x