\documentclass[a4paper,10pt,twocolumn]{article}
\usepackage[top=2cm,bottom=2cm,left=2cm,right=2cm]{geometry}
\usepackage{mathptmx}% Times Roman font
\usepackage[scaled=.90]{helvet}% Helvetica, served as a model for arial
\usepackage{xcolor}
\usepackage{amssymb}
\usepackage{times}
\usepackage[utf8]{inputenc}
\usepackage{titlesec}
\renewcommand{\thesection}{\normalsize\Roman{section}. }
\newcommand{\ssection}[1]{\section[#1]{\normalsize\centering{\textsc{#1}}}}
\date{}
\renewcommand{\thefootnote}{\arabic{footnote}}
\usepackage[runin]{abstract}
\renewcommand{\abstracttextfont}{\normalfont\small\bfseries} %% czcionka w abstract
\renewcommand{\abstractnamefont}{\normalfont\small\bfseries\slshape} %% czcionka w nazwie abstract
\abslabeldelim{--} %% separator do abstract
% odstępy/marginesy do abstract
\setlength{\absleftindent}{0pt}
\setlength{\absrightindent}{0pt}
\setlength{\absparindent}{0pt}
\setlength{\absparsep}{0pt}
\linespread{0} %interlinia
\title{\textbf {Robust model predictive control using neural networks}}
%\renewcommand{\thefootnote}{\arabic{footnote}}
\newcommand{\fna}{\footnote{K. Patan is with Institute of Control and Computation Engineering, University of Zielona Gora, Poland, \tt{k.patan@issi.uz.zgora.pl}}}
\newcommand{\fnb}{\footnote{P. Witczak is a Ph.D. student in Faculty of Electrical Engineering, Computer Science and Telecommunication, University of Zielona Góra, Poland.}}
\author{Krzysztof Patan\fna{}, Piotr Witczak\fnb{}}
\begin{document}
\maketitle
\end{document}
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This is correct and with the title, using symbols is the common thing. Do you really want numbers?
It will be a bit confusing, since by default, numbering starts all over and you might get the footnote number two times on the first page.
You should put a percent sign in front of \usepackage{times}, the package is not supported anymore.
The smart way: Calm down and take a deep breath, read posts and provided links attentively, try to understand and ask if necessary.
\documentclass[a4paper,10pt,twocolumn]{article}
\usepackage[top=2cm,bottom=2cm,left=2cm,right=2cm]{geometry}
\usepackage{mathptmx}% Times Roman font
\usepackage[scaled=.90]{helvet}% Helvetica, served as a model for arial
\usepackage{xcolor}
\usepackage{amssymb}
\usepackage[utf8]{inputenc}
\usepackage{titlesec}
\renewcommand{\thesection}{\normalsize\Roman{section}. }
\newcommand{\ssection}[1]{\section[#1]{\normalsize\centering{\textsc{#1}}}}
\date{}
\renewcommand{\thefootnote}{\arabic{footnote}}
\usepackage[runin]{abstract}
\renewcommand{\abstracttextfont}{\normalfont\small\bfseries} %% czcionka w abstract
\renewcommand{\abstractnamefont}{\normalfont\small\bfseries\slshape} %% czcionka w nazwie abstract
\abslabeldelim{--} %% separator do abstract
% odstępy/marginesy do abstract
\setlength{\absleftindent}{0pt}
\setlength{\absrightindent}{0pt}
\setlength{\absparindent}{0pt}
\setlength{\absparsep}{0pt}
\linespread{0} %interlinia
\title{Robust model predictive control using neural networks}
\usepackage{etoolbox}
\tracingpatches
\makeatletter
\patchcmd{\maketitle}{%
\renewcommand\thefootnote{\@fnsymbol\c@footnote}%
}{}{}{}
\makeatother
\newcommand{\fna}{\footnote{K. Patan is with Institute of Control and Computation Engineering, University of Zielona Gora, Poland, \tt{k.patan@issi.uz.zgora.pl}}}
\newcommand{\fnb}{\footnote{P. Witczak is a Ph.D. student in Faculty of Electrical Engineering, Computer Science and Telecommunication, University of Zielona Góra, Poland.}}
\author{Krzysztof Patan\fna{}, Piotr Witczak\fnb{}}
\begin{document}
\maketitle
\end{document}
The smart way: Calm down and take a deep breath, read posts and provided links attentively, try to understand and ask if necessary.
NEW: TikZ book now 40% off at Amazon.com for a short time.
And: Currently, Packt sells ebooks for $4.99 each if you buy 5 of their over 1000 ebooks. If you choose only a single one, $9.99. How about combining 3 LaTeX books with Python, gnuplot, mathplotlib, Matlab, ChatGPT or other AI books? Epub and PDF. Bundle (3 books, add more for higher discount): https://packt.link/MDH5p