It is a difficulty to obtain satisfactory solution based on a single structure and mechanism generally.
单一结构和机制的算法一般难以得到满意的解。
It is usually difficulty to obtain film coefficients between the working roll and the coolant fluid as we solve the temperature field of the roll.
工作辊与冷却液之间对流换热系数的确定是轧辊温度场分析的难点。
It is very difficulty to obtain the structural analysis correctly by the conventional boundary element method, when the boundary conditions is not given enough.
结构体的边界条件未能充分给出的情况下，用常规边界元法很难作出正确的结构分析。
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