After Qin Shihuang unified the whole country, his conscious achievements can be compared with those of the three emperors and five emperors. He thinks the palace in Xianyang, the capital, is too small to show his majesty to the world. In 2 12 BC, he ordered the construction of a huge palace community, Epang Palace, in the south of Weihe River and west of Zaohe River, where the Shanglin Garden in Wangjiayuan is located.

According to legend, when Qin Shihuang built the north gate of Epang Palace, he made skilled craftsmen "tired of magnets", so it was called "magnet gate". The magnet door adopts the principle of "magnet summons iron", which is similar to the modern security door.

The function of the magnet door is: first, to prevent assassins, the iron absorption of the magnet makes the hidden armor unable to pass; The second is to show the magical power to the "four barbarians", so that they are frightened and dare not have infidelity, also known as "Bird Humen".

The construction of the magnetic gate reflects the superb scientific and technological level of Qin State. This is the first time in the history of our country and even the world, and it can be said to be a great pioneering work in the history of world science and technology.

Contents and methods of modern security inspection

The content of safety inspection is mainly to check whether passengers and their luggage carry guns, ammunition, inflammable, explosive, corrosive and other dangerous goods to ensure the personal and property safety of aircraft and passengers. Passengers must go through security check before boarding the plane. Those who refuse to check are not allowed to board the plane. Those who undermine the safety of civil aviation will be punished in accordance with the Regulations on Civil Aviation Safety and Security.

The method of security inspection mainly depends on personnel and tools. Secondly, safety tools are essential. Mainly rely on the following conventional tools:

1. Hand-held metal detector: security personnel hold this equipment to conduct security inspection on the neck, elbow, back, chest and legs of the inspected person.

2. X-ray machine for security inspection: carry out perspective security inspection on personnel's luggage, check whether dangerous goods are hidden in the luggage, and prevent it from passing the security inspection.

3. Security gate: Check the inspected personnel from bottom to top in at least 6 areas. Prevent people from carrying dangerous goods such as knives and lighters.

4. Sole inspector: Detect dangerous articles on the soles of the inspected persons, such as small dangerous metal articles such as knives, lighters and detonators.