In the paper,researching into the minimum varance set,we proved that the risk of optimal portfolio may not reduce at the same expected return on increasing securities number and gave the full and essential condition of distinguishing invalid security under risk non-reducing.

Controller performance assessment method of minimum variance based on adaptive filter;

Inverse design approach for minimum variance observers;

It only needs routine closed-loop operating data and knowledge of the process time delay using minimum variance as a benchmark in controller performance assessment.

In the paper,it has been discussed that the approach of determining weights considering the expert s level with geometric mean and least-square for multi-objective group hierarchical decision making,the example is given.

The quantitative synthetical appraisement model combined weighted setting value statistic and attribute mathematics and least-square etc.

The track initiation of multi-target in dense noisy environment is concerned A method combined improved Hough transform and least-square criterion is proposed.