Latex 如何对齐属于不同{部分的方程式？

我是latex的初学者。我有下面的latex代码。代码运行良好，但我希望所有等式运算符和每个等式的“if kflag=n”对齐并写入一个等式框中，其中包含一个等式计数数。如何做到这一点

\begin{equation}    %kflag=0
\left \{
\begin{array}{rl}
T =& (1-D)\sigma_{max,0}\times e^{1-\frac{\Delta_n}{\delta_n}}\times \frac{\Delta_n}{\delta_n}\\
K =& \frac{(1-D)\sigma_{max,0}}{\delta_n}\times e^{1-\frac{\Delta_n}{\delta_n}}\times (1-\frac{\Delta_n}{\delta_n})\\
\end{array}
\right.
\quad \text{if} \quad kflag=0
\end{equation}

\begin{equation}    %kflag=1
\left \{
\begin{array}{rl}
T =& \alpha\sigma_{max,0}\times e^{1-\frac{\Delta_n}{\delta_n}}\times \frac{\Delta_n}{\delta_n}\\
K =& \frac{\alpha\sigma_{max,0}}{\delta_n}\times e^{1-\frac{\Delta_n}{\delta_n}}\times (1-\frac{\Delta_n}{\delta_n})\\
\end{array}
\right.
\quad \text{if} \quad kflag=1
\end{equation}

\begin{equation}    %kflag=2
\left \{
\begin{array}{rl}
T =& (1-D)\sigma_{max,0}\times e^{1-\frac{\Delta_n}{\delta_n}}\times \frac{\Delta_n}{\delta_n}+T_{max}-\\
&(1-D)\sigma_{max,0}\times e\times\frac{\Delta_{max}}{\delta_n}+\\
&10\times \sigma_{max,0}\times e^{1-\frac{\Delta_n}{\delta_n}}\times \frac{\Delta_n}{\delta_n}\\
K =& 11\times\frac{(1-D)\sigma_{max,0}}{\delta_n}\times e^{1-\frac{\Delta_n}{\delta_n}}\times (1-\frac{\Delta_n}{\delta_n})\\
\end{array}
\right.
\quad \text{if} \quad kflag=2
\end{equation}

\begin{equation}    %kflag=3
\left \{
\begin{array}{rl}
T =& T_{max}+K\times(\Delta_n-\Delta_{max})\\
K =& \frac{(1-D)\sigma_{max,0}*e}{\delta_n}\\
\end{array}
\right.
\quad \text{if} \quad kflag=3
\end{equation}

现在方程是这样的

---

这里有一个选项，使用大量嵌套结构-

等式

进行编号，

对齐

进行结构水平对齐，

dcase

（或

案例

）进行左括号内容

\documentclass{article}

\usepackage{mathtools}

\begin{document}

\newcommand{\Ddn}{\frac{\Delta_n}{\delta_n}}
\newcommand{\smz}{\sigma_{\mathrm{max}, 0}}

\begin{equation}
  \begin{aligned}
    &\begin{dcases}
      \phantom{K}\mathllap{T} = (1 - D) \smz \times e^{1 - \Ddn} \times \Ddn \\
      K = \frac{(1 - D) \smz}{\delta_n} \times e^{1 - \Ddn} \times \bigl( 1 - \Ddn \bigr)
    \end{dcases} & \text{if $k$-flag} = 0 \\ % k-flag = 0
    &\begin{dcases} 
      \phantom{K}\mathllap{T} = \alpha \smz \times e^{1 - \Ddn} \times \Ddn \\
      K = \frac{\alpha \smz}{\delta_n} \times e^{1 - \Ddn} \times \bigl( 1 - \Ddn \bigr)
    \end{dcases} & \text{if $k$-flag} = 1 \\ % k-flag = 1
    &\begin{dcases}
      \phantom{K}\mathllap{T} = \begin{aligned}[t]
        &(1 - D) \smz \times e^{1 - \Ddn} \times \Ddn + T_{\mathrm{max}} \\
        &{} - (1 - D) \smz \times e \times \frac{\Delta_{\mathrm{max}}}{\delta_n} \\
        &{} + 10 \times \smz \times e^{1 - \Ddn} \times \Ddn
      \end{aligned} \\
      K = 11 \times \frac{(1 - D) \smz}{\delta_n} \times e^{1 - \Ddn} \times \bigl( 1 - \Ddn \bigr)
    \end{dcases} & \text{if $k$-flag} = 2 \\ % k-flag = 2
    &\begin{dcases}
      \phantom{K}\mathllap{T} = T_{\mathrm{max}} + K \times (\Delta_n - \Delta_{\mathrm{max}}) \\
      K = \frac{(1 - D) \smz \times e}{\delta_n}
    \end{dcases} & \text{if $k$-flag} = 3
  \end{aligned}
\end{equation}

\end{document}