Using Case-Based Reasoning method to supply chain risk assessment, it successfully solves the problems like how to describe and save cases, how to find matching case, how to adjust the solution, etc.

Firstly,this paper introduces the development of the security of network and information in today s China,analyses the problems and the corresponding solving methods and strategies,then it introduces the risk evaluation of the security of network and information and the quantitative evaluation of threat.

Concerning the risk estimation,Bunke discussed the minimax of the best linear unbiassed estimator of a multiparameter controled statistical model which has the quadratic loss function with the positive definite "weighting" matrix.

This paper analyzes risk factors and risk events in accordance with risk discernment , risk estimation and risk assessment.

(4) The principle and methods of construction risk estimation for subway station are discussed.

It introduces the definition of risk estimate, and points that the probability, extent and the relation of risk factors are the decisive factor to the risk estimate, and then it studies risk coordinative coefficient.

This paper systemically introduces some basic theories on engineering construction risk management, and combines with characteristics of bridge construction to analyze risk identification, risk estimate, risk evaluation and risk handling during bridge construction stage with different theoretical models.