Untitled

        \begin{tikzpicture}
            \begin{axis}[axis x line = bottom, axis y line = left, xlabel = {Temps \emph{t} écoulé}, ylabel = {Processus actif ou non}, width = 17 cm, height = 3 cm, xmin = 0, ymin = 0, xmax = 15, ymax = 1]
                \addplot[color=white] coordinates { (0,0) };

                \addplot[color=white] coordinates { (2,0) };
                \addplot[color=white] coordinates { (2,1) };
                \addplot[color=white] coordinates { (5,1) };
                \addplot[color=white] coordinates { (5,0) };

                \draw (2,0) -- (2,1);
                \draw (2,1) -- (5,1);
                \draw (5,0) -- (5,1);

                \addplot[color=white] coordinates { (6,0) };
                \addplot[color=white] coordinates { (6,1) };
                \addplot[color=white] coordinates { (8,1) };
                \addplot[color=white] coordinates { (8,0) };
                \draw (6,0) -- (6,1);
                \draw (6,1) -- (8,1);
                \draw (8,0) -- (8,1);

                \addplot[color=white] coordinates { (10,0) };
                \addplot[color=white] coordinates { (10,1) };
                \addplot[color=white] coordinates { (11,1) };
                \addplot[color=white] coordinates { (11,0) };
                \draw (10,0) -- (10,1);
                \draw (10,1) -- (11,1);
                \draw (11,0) -- (11,1);

                \addplot[color=white] coordinates { (12,0) };
                \addplot[color=white] coordinates { (12,1) };
                \addplot[color=white] coordinates { (14,1) };
                \addplot[color=white] coordinates { (14,0) };
                \draw (12,0) -- (12,1);
                \draw (12,1) -- (14,1);
                \draw (14,0) -- (14,1);
            \end{axis}
        \end{tikzpicture}