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\begin{document}
    \Large
    % \begin{eqnarray*}
    %   & &
    %   \DP{\phi}{t}  = \kappa \Dlapla \phi, \quad
    %   % \phi = 0 \ \mbox{at} \ y=y_{min},y_{max}, 
    %   % \DP{\phi}{y} = 0 \ \mbox{at} \ y=y_{min},y_{max}, 
    %   % \DP{\phi}{y} = 0 \ \mbox{at} \ y=y_{max}, \quad
    %   %   \phi = 0 \ \mbox{at} \ y=y_{min}, 
    %   % \phi = 0 \ \mbox{at} \ y=y_{max}, \quad
    %   %   \DP{\phi}{y} = 0 \ \mbox{at} \ y=y_{min}, 
    %   % \\
    %   \\ & &
    %   \left.\DD{\tilde{\phi}_{k}}{y}\right|_{y_{max}}
    %           +k\tilde{\phi}_{k}|_{y_{max}}=0, \quad
    %   \left.\DD{\tilde{\phi}_{k}}{y}\right|_{y_{min}}
    %           -k\tilde{\phi}_{k}|_{k_{min}}=0.
    %   \\
    %   & & \qquad
    %   \tilde{\phi}_k(y,t) = \int \phi(x,y,t)e^{ikx} dx, 
    %   \\
    %   & & \qquad
    % \Dlapla = \DP[2]{}{x} + \DP[2]{}{y}
    %              \quad \kappa \mbox{: const.}
    % \end{eqnarray*}

    % �󰵽�ή��Ȼ�����
    \begin{eqnarray*}
      & &
      \DP{}{t} (\Dlapla \phi) = \nu \Dlapla\Dlapla \phi, \quad % \\ & & % \quad
      % \phi = \DP{\phi}{y} = 0 \ \mbox{at} \ y=y_{min},y_{max}, \\
      \phi = \DP[2]{\phi}{y} = 0 \ \mbox{at} \ y=y_{min},y_{max}, \\
      % \phi = \DP{\phi}{y} = 0 \ \mbox{at} \ y=y_{max}, \quad
      % \phi = \DP[2]{\phi}{y} = 0 \ \mbox{at} \ y=y_{min}, \\
      % \phi = \DP[2]{\phi}{y} = 0 \ \mbox{at} \ y=y_{max}, \quad
      % \phi = \DP{\phi}{y} = 0 \ \mbox{at} \ y=y_{min}, \\
      & & \qquad
      \Dlapla = \DP[2]{}{x} + \DP[2]{}{y}
                \quad \nu \mbox{: const.}
    \end{eqnarray*}
 
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