Question: Integro-Differential Equations

This is my system: rho * diff(diff(delta(x, y, t), t), t) = (y ^ 2 / 0.2e1 - d ^ 2 / 0.8e1) * Y * diff(diff(diff(diff(xi(x, y, t), x), x), x), x) + (((2 * G + lambda) * v - lambda) * diff(diff(xi(x, y, t), x), x)) + 0.16e2 * Q(t) ^ 2 * y * (d ^ 2 - 0.2e1 * y ^ 2) / d ^ 4 / b ^ 2 / l ^ 2 / e; diff(delta(x, y, t), y) = v * y * diff(diff(xi(x, y, t), x), x); i = 0.8e1 * Df * Q(t) / d ^ 2 + l * Lp * (int((2 * G + lambda * (v - 1)) * diff(diff(xi(x, y, t), x), x), x == (0..b)) + Y * d ^ 2 * int(diff(diff(diff(diff(xi(x, y, t), x), x), x), x), x == (0..b)) / 0.12e2) + diff(Q(t), t); My objective is to obtain the expression of delta,xi and Q to the space coordinates(x,y) and time,t.The other letters are constants. Can the maple do this? I try with pdsolve but obtain this error: "Error, (in pdsolve/sys) not implemented for composite functions of the unknowns of the system as in int(diff(diff(diff(diff(xi(x, y, t), x), x), x), x), x = 0 .. b)" Can I obtain a solution of the system another away?Maybe a numeric method.
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