Based on the unascertained characteristics of river water environmental system, such two concepts as unascertained parameters of water quality system and unascertained risk of river water quality are defined.

On the basis of introduction of water environment paramatric blind number with grey uncertainty and unascertained uncertainty, unascertained risk concept and measure are put forward, and corresponding form of expression and method for calculation are set up also.

Calculation of water environmental capacity in lake and reservoir based on unascertained number theory;

Qualitative estimation method of equipment life cycle cost based on unascertained number theory;

In this paper, the correspondence K from the real number set R to the subset R of the unascertained number set R has been given here.

Like other environmental systems, lake and reservoir are also complicated systems with uncertainty.

The specified probabilistic models for structural resistances were put forward in connecting with the differences between both structures in deign and in service, which introduce the uncertainty variables into probabilistic models for the in-service structural resistance to reflect the uncertainty of cognit.

The unascertained mathematics analysis method of the measurable results about the dissolved oxygen of water;

The unascertained mathematics was introduced to analyze the representative values of compressive strength of concrete core from cast in-suit pile at the condition of small sampling data.