Open the SCR keyhole with a sharp object. If you can't get it out yourself, find a professional locksmith to open it, or go to a repair shop to repair it. SCR system, selective catalytic reduction technology SCR is a treatment technology of nitrogen oxides in diesel vehicle exhaust, that is, ammonia or urea is injected under the action of catalyst to reduce nitrogen oxides in exhaust to N2 and H2O.

Keyhole history

Peeping through keyhole becomes more useful. Now, an imaging technology allows spies to draw a map of the whole room through small holes. This technology uses measuring the laser path to construct a three-dimensional image.

In 20 12, researchers used lasers to observe objects at corners. This system sends short laser pulses to a nearby wall, reflecting the light to a hidden ball on the other side of the corner, and the ball reflects part of the light back to the camera next to the laser.

This camera can only measure incident light in a short time. With some adjustments, we can measure the light passing through different distances, thus establishing 3D images of hidden objects.

Now Jin of Harbin Institute of Technology in China and his colleagues have done further work. They used laser equipment to measure the shape and position of the letter "HIT" made of three pieces of cardboard through a 2 cm hole in the nearby wall.

This time, the light returning from the object reaches the other wall through this small hole, which scatters the light to the camera. By pointing the camera at different parts of the wall, researchers can scan previously hidden rooms.