The frequency of sound waves perceived by human ear ranges from 16Hz to 20 kHz. The sound waves below 16 Hz are called infrasound waves, while the sou

After understanding the classification of industrial cleaning, we can choose suitable cleaning process according to object to be cleaned to achieve th

Cleaning is a civilized labor. "Cleaning", a kind of subconscious or unconscious labor, has been accompanied by the development of human beings from t