dt=[10  20 30 40 80];
 for j=1:5
alfa(j)=(32/(pi^2))*(1/(dt(j))^3);
beta(j)=(4/pi)*(1/(dt(j)^2));

v=1:1:150;
for   i=1:150
   u(i)=alfa(j)*v(i)^2*exp(-beta(j)*v(i)^2);
   end
   plot(v,u)
   hold on
   end