大家好。我收到此错误：
pdflatex.exe：连接尝试失败，因为连接方在一段时间后没有正确响应，或者建立连接失败，因为连接的主机未能响应。pdflatex.exe：数据：tcp_connect() 中的连接失败
这使得我的代码需要很长时间才能编译，尽管它似乎编译正确。我正在使用 pdflatex 进行编译。有人遇到过同样的问题吗？
我的脚本：
\documentclass[paper=a4]{article} % A4 paper and 11pt font size
\usepackage[english]{babel} % English language/hyphenation
\usepackage{amsmath,amsfonts,amsthm} % Math packages
\usepackage{graphicx}
\begin{document}
\begin{titlepage}
\thispagestyle{empty}
\end{titlepage}
\setcounter{page}{1}
\newpage
\section*{Introduction}
The purpose of this project is to
\subsection*{Problem}
The system to be analysed through the duration of this project is a two-car train, interconnected with a spring, as shown in Figure 1:\\
\newline
\begin{figure}[h!]
\centering
\includegraphics[scale=0.5]{System1.png}
\caption{two-car train, interconnected with a spring}
\end{figure}
\newline
It was initially proposed to use the absolute displacements of the carts as state variables, but it turns out that this results in the system becoming unobservable. The choice was thus made to choose the state variables:\\
\begin{align}
x =
\begin{bmatrix}
\Delta \\
v_1 \\
v_2
\end{bmatrix}
\end{align}
where $v_1=\dot{z_1}$ and $v_2=\dot{z_2}$ are the speeds of cars 1 and 2, respectively.\\
Note that we are dealing with a third order system, as we have 3 state variables.
\newline
The state equation of the system is given by:\\
\begin{figure}[h!]
\centering
\includegraphics[width=0.5\textwidth]{state_eqn.png}
\end{figure}
\newpage
and the observation equation by:\\
\begin{figure}[h!]
\centering
\includegraphics[scale=0.1]{obs_eqn.png}
\end{figure}
\newline
We thus have a single input single output (SISO) system with the voltage going to the motor of the first car as the input and the speed of the first car as the output.\\
We now substitute the following constants into the dynamics matrix A, the input matrix B and the observation matrix C:\\
\begin{center}
$M_1=M_2=1kg$\\
$K=40N/m$\\
$k=2Vs$\\
$R=100\Omega$\\
$r=2cm$\\
\end{center}
We then get the following matrices:\\
\begin{align}
A =
\begin{bmatrix}
0 & -1 & 1 \\
40 & -0.01 & 0 \\
-40 & 0 & 0
\end{bmatrix}\\
\end{align}
\begin{align}
B =
\begin{bmatrix}
0\\
0.01\\
0\\
\end{bmatrix}
\end{align}
\begin{align}
C =
\begin{bmatrix}
0 & 1 & 0\\
\end{bmatrix}
\end{align}
\subsection*{Controllability and observability}
Before we start the analysis, it will be useful to confirm that the system at hand is indeed controllable and observable.\\
\newline
To be controllable, the rank of the controllability test matrix, defined by\\
\begin{align}
Q =
\begin{bmatrix}
B & AB & A^{2}B
\end{bmatrix}
\end{align}
has to be of the same order as the system. To be observable, the rank of the observability test matrix, defined by\\
\begin{align}
N =
\begin{bmatrix}
C' & A'C' & A'^{2}C'
\end{bmatrix}
\end{align}
has to be of the same rank as that of the system. Computing matrices Q and N and using the rank() function in MATLAB shows that the ranks of both matrices are 3, and thus equal to the order of the system. We now know that the system is controllable and observable and can thus use the tools at our disposal to design a controller for this system.
\section*{Question A}
Assuming all states are measured for feedback purposes, we will now determine the gain matrix
\end{document}
答案1
如果您使用 MiKTeX 并尝试“即时”安装软件包，pdfTeX 仅需要访问互联网。因此，这里的情况正是这种情况。此过程可能会出现网络问题，也可能出现配置错误。例如，有时 MiKTeX 服务器网络不可用，导致无法安装软件包。因此，这里的答案是“检查您的设置、MiKTeX 服务器状态，然后等待”，至少没有更多细节（哪个 MiKTeX 软件包和服务器导致出现问题，ETC。）