代码：
\documentclass[UTF8,a4paper,12pt,hyperref]{ctexart}
\usepackage[left=3.18cm,right=3.18cm,top=2.54cm,bottom=2.54cm]{geometry}
\begin{document}
\begin{abstract}%中文摘要
调制在通信系统中有至关重要的作用，其基本思想是用调制信号（原始基带信号）控制载波参数，使载波信号中一个或数个参数随着调制信号的规律产生变化采用调制技术主要是为了实现多路复用，提高信道利用率和系统抗干扰、抗衰落的能力，以及提高电磁波发射效率等。在传输过程中，已调信号总会受到噪声的干扰，实验结果表明，干扰噪声是各态历经的平稳高斯白噪声，经过系统传输后接收到的信号为余弦信号加平稳窄带高斯噪声。这里以双边带调幅及相干解调为例，分析余弦信号加窄带高斯过程在通信系统中的应用。
%\centering%使得关键字居中
\newline
\textbf{关键字：}窄带随机信号,白噪声,通信系统,调制
\end{abstract}
\ctexset{
abstractname = {Abstract},%显示英文摘要
}
\begin{abstract}
Modulation plays a vital role in the communication system. The basic idea is to control the carrier parameters with the modulated signal (original baseband signal), so that one or several parameters in the carrier signal change with the law of the modulated signal. It is to achieve multiplexing, improve channel utilization and system anti-interference, anti-fading ability, and improve electromagnetic wave emission efficiency. During the transmission process, the modulated signal will always be interfered by noise. The experimental results show that the interference noise is the smooth Gaussian white noise experienced by various states. After the system transmits, the received signal is the cosine signal plus the stationary narrow-band Gaussian noise. Here, the double-band (DSB) amplitude modulation and coherent demodulation are taken as an example to analyze the application of the cosine signal plus the narrowband Gaussian process in the communication system.
%\centering
\newline
\textbf{Keywords:} Narrowband random signal ,White noise ,Communication system Codulation
\end{abstract}
\section{section name} % (fold)
\label{sec:section_name}
调制在通信系统中有至关重要的作用，其基本思想是用调制信号（原始基带信号）控制载波参数，使载波信号中一个或数个参数随着调制信号的规律产生变化采用调制技术主要是为了实现多路复用，提高信道利用率和系统抗干扰、抗衰落的能力，以及提高电磁波发射效率等。在传输过程中，已调信号总会受到噪声的干扰，实验结果表明，干扰噪声是各态历经的平稳高斯白噪声，经过系统传输后接收到的信号为余弦信号加平稳窄带高斯噪声。这里以双边带调幅及相干解调为例，分析余弦信号加窄带高斯过程在通信系统中的应用。
% section section_name (end)
\end{document}
结果是这样
