1. The model uses mean absolute deviation of return as measure of the risk and gains a optimal portfolio by solving the linear programming.

2. As a measure of risk, mean absolute deviation is better than variance in a sense.

3. The mean absolute deviation of the calculation results by this method from the experiment data was 14.9%.

4. Entropy, standard deviation, mean absolute deviation of the PD gray images are extracted and the acquired characteristics are analyzed for five types of discharge pattern recognition.

5. Consequently, it is also necessary to estimate the forecast error, which may be represented by the standard deviation or the Mean Absolute Deviation(MAD).