%\documentclass[english,onecolumn,final]{svjour2}
\documentclass{article}
\usepackage{graphicx}
\usepackage{tikz}
\usepackage{pgflibraryshapes}
\usetikzlibrary {shapes}
\usepackage{calc}
\usepackage{color}
\definecolor{invisible}{gray}{1.0}
\definecolor{green}{rgb}{0.0,1.0,0.0}
%\input{commands.tex}
%define counters
\newcounter{mynum}

%\renewcommand\normalsize{\fontsize{20pt}{20pt}\selectfont}

\setlength{\textwidth}{20cm}
\setlength{\textheight}{30cm}

\pagenumbering{arabic}  % but no page numbers are printed because:
\pagestyle{empty}       % this is actually already in the kernel
\newcommand{\MainDocDir}{..}

\begin{document}

\newcommand{\texpic}{
  \begin{tikzpicture}

    \draw (0,0) node (gui) [shape=rectangle,draw, minimum width=2cm, minimum height=1cm] {GUI (tcl/tk)} ;
    \draw (gui.south) ++(-3,-1) node (sh) [shape=rectangle,draw,anchor=north] {\parbox{2cm}{\center start/stop\\ (sh)}};
    \draw[-latex] (gui) -- (sh) ;
    \draw (sh.south) ++(0,-1) node (sim) [shape=rectangle,draw,anchor=north] {\parbox{2cm}{\center simulation \\ (c++)}};
    \draw[-latex] (sh)--(sim);
    \draw (sim.east) ++(0.5,0) node (data) [shape=rectangle,draw,anchor=west] {\parbox{3cm}{\center simulation data\\(\$HOME/data/...)}} ;
    \draw[-latex] (sim)--(data);
        \draw (data.east) ++(0.5,0) node (vis) [shape=rectangle,draw,anchor=west] {\parbox{2cm}{\center visalization\\(IDL)}} ;
       \draw[-latex] (data)--(vis);
       \draw[-latex] (gui)--(vis);
       \draw[-latex,dashed] (sim) .. controls +(40:3cm) and +(0,-1) .. (gui);
  \end{tikzpicture}
}

\color{invisible}
.\\
.
\color{black}
\texpic
\color{invisible}
.
\end{document}