function [cost,d_model]=cost2_beam(CK,time,disp)
m=length(disp);
weight=ones(m,1);
weight(1:2200)=100;
weight(3500:m)=2;
x0 = [disp(1) 0];
C = CK(1);
K = CK(2);
[t,x] = ode23(@ode_model, time, x0, [], C, K);
d_model = x(:,1);
cost = sum(weight.*(d_model-disp).^2);