\documentclass[11pt]{article}

%\journal{Thermal Science}
\usepackage[UTF8x]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[frenchb, english]{babel}
\usepackage{graphics}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{lineno}
\usepackage{pict2e}
\usepackage{float}
\usepackage{array}
\usepackage{multirow}
\usepackage{ltugcomn}
\usepackage{stfloats}

\usepackage[numbers, sort]{natbib}

\setlength{\unitlength}{1pt} % for the picture environment

%\usepackage{endfloat}

\renewcommand{\floatpagefraction}{2}
%\renewcommand{\textfraction}{2}

\usepackage{ifpdf}
	\ifpdf
		\graphicspath{{}}
		\usepackage{graphicx}
		\DeclareGraphicsExtensions{.jpg}
		\usepackage[pdftex]{hyperref}
	\else
		\graphicspath{{}}
		\usepackage{graphicx}
		\DeclareGraphicsExtensions{.eps, .ps}
		\usepackage[T1]{fontenc}
	\fi



\usepackage{times}
\usepackage{geometry}
\geometry{margin=25mm}
%%%% debut macro %%%%
\newenvironment{changemargin}[2]{\begin{list}{}{%
\setlength{\topsep}{0pt}%
\setlength{\leftmargin}{0pt}%
\setlength{\rightmargin}{0pt}%
\setlength{\listparindent}{\parindent}%
\setlength{\itemindent}{\parindent}%
\setlength{\parsep}{0pt plus 1pt}%
\addtolength{\leftmargin}{#1}%
\addtolength{\rightmargin}{#2}%
}\item }{\end{list}}
%%%% fin macro %%%%
\usepackage[font={bf, small}]{caption}
\setlength\topsep{-8pt plus 0pt minus 0pt}

\begin{document}

\baselineskip=16pt

\begin{center}
\textbf{ }\\
~~\\
\textbf{ }\\
~~\\
%corresponding author: 
%tel: , fax: 
{\small } 
\end{center}

\begin{changemargin}{2cm}{2cm}
\textit{ \\ 
~~\\
Keywords }
\end{changemargin}

\section{Introduction}

\section{}

\section{}

\subsection{}

\subsection{}

\subsubsection{}

\subsubsection{}

\subsubsection{}
	
\subsection{ }

\subsubsection{}

\subsubsection{}

\subsubsection{}

 
\subsection{}


\section{Conclusion}



\section*{Nomenclature}

\end{document} 

