This paper provides the calculation measure of number of overhand insulator in power plant and substation for this calculation is necessary for electrical system design and is a difficult point,at same time,emends the minimum number of overhand insulator in power plant and substation in the standard of conductor and electrical equipment choice after dirtiness degree have been emended.

This paper firstly analyzed the security and efficiency of the Ji-Li s proxy multi-signature scheme and pointed out two problems existed in the Ji-Li s proxy multi-signature scheme:a)Security,didn t possess the strong unforgeability property because of not being able to avoid the suspending-factor,anyone of the multi-original signers could forge a valid proxy multi-signature for any message.

The authors introduce the concept of suspending-factor, and definitely point out that it must be avoided in designing signature schemes.

With the analysis of the signature scheme,"A Designed Group-receiver Strong Proxy Signature Scheme",which was put forward by Chen-Xu(2007),the paper points out that it does not posses the strong unforgeability property because of not being able to avoid the suspending-factor.

Study on Computation Methods of Windage of Suspension Insulator Strings under Dynamic Wind Loads;

Test and research result shows that the retrofit of backward V insulators can be carried out for 500 kV suspension insulator string, and when it is .

The electric field distribution on 500kV power transmission tower suspension insulator string and metal fittings is calculated adopting the finite element method (FEM) considering the audible noise on such towers.