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The rapid development of air filters is closely related to the development of military industry and electronic industry. In the first world war, the use of various chemical agents, asbestos fibre filter paper as the smoke filter layer of military gas masks came into being. The glass fiber filter medium is used in air filtration to obtain a patent in the United States in October 1940. In the 1950s, the United States studied the production process of glass fiber filter paper, and the air filter was improved and developed. In the 1960s, HEPA filters came out; In the 1970s, the filter paper of fine glass fiber was used as the HEPA filter of filter medium, and the filtration efficiency of particle size of 013 micron particle diameter was 99.9998%. Since the eighty s, with the emergence of new test method, use evaluation to improve and to improve the filtering performance requirements, found the HEPA filter there is a serious problem, and he had a higher ULPA filter performance. Countries are still working on it and expect more advanced air filters soon
Most new cars have built-in GPS GPS systems for cars and trucks are incredibly useful since you can find out where you stand when you get lost or find your motor vehicle if it has been stolen. Parents may also be with your GPS systems to hold track of new teenage drivers.
Signs of birth. Since the middle of the 20th century, technology has grown faster and faster. It was only six and a half years since the discovery of uranium fission in January 1939 to the first atomic bomb exploded in July 1945. The emergence of electronic computers has led to more profound changes in the fields of human social life. These technological breakthroughs can be called technological revolutions
The history-making earthquake and tsunami have caused the most serious nuclear accidents in Japan's Fukushima Daiichi nuclear plants ' our planet's most devastating nuclear disaster since Chernobyl and Three Mile Island. The first massive explosion and leak happened on March 12, 2011 at the Fukushima Daiichi atomic power plant. Despite all immediate efforts to cool along the reactors, reactor No.3 and three other reactors lost its ability to chill on Sunday. The fact results in three massive hydrogen explosions in Fukushima Daiichi nuclear plant, which sends enormous column of smoke in the air. An estimated of greater than 180,000 individuals have evacuated. More dangerously, the radioactive leakage has raised rays levels across the plant higher than the safety limit. 160 folks are being exposed to radiation.
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