% This is only an example to test the environment! Replace with your own text!
\chapter{Introduction}
\lipsum[3]	
\section{Background}
\lipsum[4]	

\begin{align}
	\hat{s_{i}} &= \int_{0}^{T_{s}} r(t)\cdot g(t)\cdot \cos(2\pi f_{i}t+\phi_{i}) dt \nonumber\\
	&= \int_{0}^{T_{s}} \left[\sum_{j=0}^{N-1}s_{j}\cdot g(t)\cdot  \cos(2\pi f_{j}t+\phi_{j})\right] \cdot g(t)\cdot  \cos(2\pi f_{i}t+\phi_{i})dt \label{equ:3.3.1} \\
	&= \sum_{j=0}^{N-1}  s_{j} \int^{T_{s}}_{0} g(t)^{2}\cdot \cos\left(2\pi \left(f_{0}+\frac{j}{T_{s}}\right)t+\phi_{j}\right) \cdot \cos\left(2\pi \left(f_{0}+\frac{i}{T_{s}}\right)+\phi_{i}\right) dt \nonumber \\
	&= \sum_{j=0}^{N-1} s_{j}\cdot \delta(j-i)\nonumber \\
	&= s_{i}.\nonumber
\end{align}
\begin{figure}
	\centering
		\includegraphics[width=.85\textwidth]{figures/figure1.png}
	\caption{No daily life without electrical engineering \cite{eit}}
	\label{fig:figure1}
\end{figure}

