Based on the overload-protective working demands of series JZ21 Baromectric Press,the paper introduces a overload-protective system of Barometric Press,the core of which is pneumatic pump and safety protective valve.

And the main performances,technical parameters,safety protection system and actual application results are analyzed and summarized.

Multiform safety protection and alarming functions are set for disc brake which provides multi-braking functions.

This paper introduces the functions and control theory of PLC's main components,expounds the application of twelve kinds of safety protection techniques in the large-scale belt transporter,and advances the deficiencies existing in the safety protection techniques.

Improvement of the safeguard device for the control system of electric gateway;

The protection will help to safeguard the coal mine dramatically.

Brief talk on entity and security protection of electronic document;

： Information security is becoming more and more important．This paper realizes a kind of protective system of information security．It deals with information importation，security protection and compressive transmission．The major techniques it involved are information carrying and information divided－storing

The security protection for Chinese people overseas is an important issue in the study of diplomacy.