Under the background of DATIAN doub- le-arch tunnel in construction of the Tonghuang Highway,cyclic variable method is used to optimize the parameters of SVM based on SVM algorithm in order to present the nonlinear relation between the data,meanwhile the nonlinear model for displacement is established.

Compared to other widely used direct search method,random search methods and cyclic variable method have the advantages of simpleness and clear,easily programmed and smple implementation,especially when the gradient is burdensome or impossible to calculate.

The cyclic variable method is used to optimize parameters of SVM so as to establish the nonlinear time series model.

Based on the virtue of constrained cyclic variable method, a set of new search directions is proposed to enhance the performance of constrained cyclic variable method in this paper, and the improved method was similar in the iterative steps to constrained cyclic variable method.

With proper method of variable substitution, the soluble method to two kinds of inegrable equation of Riccati form is found, and the general integral expressions are given.

It is offered Euler differential equations depending on a parameter λ,and given the general solution formula express of them by method of variation replacement,method of variation position transformation,method of linearization,and method of reduction of order.

Two types of new Abel differential equation are structured by method of variation replacement, variation position transformation and compound function derivation law.

Application of "variable substitution" in higher mathematics;

Compared with the traditional converter transformer,the new-type converter transformer has particular connection scheme,for which the remnant conversion method is proposed to calculate its short-circuit faults.