Infrasound waves from the internet are sounds less than 20 Hz. What's the use of infrasound? ① Meteorological and earthquake prediction services. For example, jellyfish, a lower marine animal, is particularly sensitive to infrasound waves of 8- 13 Hz. According to the jellyfish ear structure bionics, the jellyfish ear typhoon predictor can predict the direction and intensity of typhoon 15 h in advance. (2) to serve national defense construction. Establish infrasound service stations to detect and analyze major military trends such as nuclear explosions and rocket launches around the world. At present, a particularly sensitive infrasound detector has been developed, which can be used in border inspection to see if anyone is mixed with the luggage of vehicles. ③ In agriculture and forestry production, infrasound is used to treat tree diseases and stimulate plant growth. ④ For human production, a proper dose of 8- 12Hz infrasound can make people concentrate their thinking. Infrasound mosquito repellent is used to prevent mosquito bites. Infrasound means that the frequency is less than 20Hz (Hz. The human ear is basically insensitive to infrasound, but some animals such as elephants, giraffes and blue whales can feel infrasound frequency and use it to communicate. In particular, infrasound waves with extremely low frequency can travel far. Infrasound waves also travel far underwater. Infrasound waves are not easily attenuated and absorbed by water and air. Infrasound often has a long wavelength, so it can be diffracted around some large obstacles. Some infrasound waves can circle the earth two or three times. Physiological and psychological effects Although people can hardly hear infrasound, they can feel infrasound through its wave pressure. But the hearing loss is very high, and it varies with frequency [1]. In addition, the body can also feel the low-frequency violent vibration. Although there has been a legend about infrasound's harm to human body, there is no experiment to prove that infrasound with sound pressure below 170 dB has any harm to hearing, balance organs, lungs or other internal organs [2]. The human eardrum will rupture at about 185 to 190 decibels, which is equivalent to half a standard atmospheric pressure. Infrasound waves with extremely low frequency, extremely long exposure time and extremely high vibration acceleration (the amplitude acceleration exceeds the acceleration of the earth's gravity) can lead to visceral bleeding in some cases. Under such high-amplitude infrasound waves, people can feel infrasound waves (like ordinary sound waves) and have psychological effects, especially inattention. There have been heated discussions about the role of wind turbines, hum and organ sounds, but it has not been proved that the imperceptible infrasound has any influence on people. [Editor] Sound source [Editor] The low-frequency waves of natural sound sources such as earthquakes, volcanic eruptions, falling meteorites, extreme weather phenomena or huge waves can cause infrasound waves in the air. This infrasound wave can travel several Qian Qian meters. Gusts and tornadoes also produce infrasound waves. [Editor] Foehn wind in Alps is a very strong infrasound source, and its frequency is between 0.0 1 ~ 0. 1 Hz. Whether this infrasound has an impact on people is still controversial. [Editor] Artificial sound source industrial facilities will also produce infrasound waves. In particular, if infrasound waves form a standing wave in a closed room, it will make the building structure vibrate and cause harm. The sound produced by ground or underground explosions and rockets contains infrasound. These infrasound waves can travel far, and they can be used to determine the location or direction of an explosion or rocket launch. The sonic boom when a supersonic plane breaks through the sound barrier contains infrasound. Especially in large cities with dense buildings, infrasound waves will be generated. Such infrasound waves will not only travel far, but also produce strong standing waves locally. For example, there are many tall buildings in some urban areas of DC, USA. These buildings mainly use hard stone surfaces, and almost all of them have very powerful air-conditioning devices. In summer, there will be a wide range of infrasound fields in cities, and the airflow between buildings will interact to produce low-frequency vibration. Especially in very quiet nights, low-frequency sound waves in big cities can still be heard in very far places, and secondly, the components of sound waves spread further. Some people think that living in such a infrasound field for many years will lead to health problems. Whether infrasound produced by wind turbines has an impact on health has been controversial, but so far there is no data to prove this impact. However, wind turbines also produce auditory and physiological low-frequency sound waves. [Editor] Sometimes it is difficult to find the sound source of infrasound. High-amplitude infrasound often produces nonlinear effects and harmonics, which can often be heard, simplifying the process of finding sound sources. People use barometric detectors to detect and measure infrasound waves. Unlike barometers, this detector has a fast response and can measure very small pressure changes. Unlike microphones, they can detect sound waves with frequencies as low as 0.0 1 to 0. 1 Hz. The study of infrasound waves in the atmosphere and ocean is a relatively new topic. Its application scope includes determining nuclear explosion test and ship motion. [Editor] Infrasound Monitoring Network After the signing of the Comprehensive Nuclear-Test-Ban Treaty, the international infrasound monitoring network was established all over the world. The purpose of this monitoring network is that any nuclear explosion in the atmosphere, underwater or space will not be ignored. The data of this monitoring network can also be used to detect and locate non-nuclear explosions and other secondary sound sources. Ultrasonic technology is one of the general technologies based on physics, electronics, machinery and materials science. Ultrasonic technology is accomplished through the physical process of ultrasonic generation, propagation and reception. Ultrasonic wave has the characteristics of bunching, orientation, reflection and transmission. According to the different size of ultrasonic vibration radiation, it can be roughly divided into: 1. The power application that changes objects or physical properties with ultrasonic waves is called power ultrasound. For example, enough energy occurs in the liquid to generate cavitation, which can be used for cleaning and emulsification. 2. The application of using ultrasonic waves to obtain some information and obtain communication is called detecting ultrasonic waves. For example, measuring the thickness of an object by pulse reflection of ultrasonic waves in a medium is called ultrasonic thickness measurement. Ultrasonic cleaning and application: ultrasonic cleaning principle ultrasonic cleaning belongs to physical cleaning, cleaning solution is put into the tank, and ultrasonic wave acts in the tank. Because ultrasonic wave is a kind of dense vibration wave similar to sound wave, the pressure of the medium changes alternately during its propagation. In the negative pressure area, tearing force is generated in the liquid, and vacuum bubbles are formed. When the sound pressure reaches a certain value, the bubbles grow rapidly, and in the positive pressure area, the bubbles are crushed and closed due to pressure extrusion. At this point, the liquids collide with each other to produce a powerful shock wave. Although the displacement and velocity are small, the acceleration is large, and the local pressure can reach several thousand atmospheres, which is the so-called cavitation effect. Second, several factors affecting the cleaning effect 1, the relationship with frequency: the lower the general frequency, the more obvious the effect, but the noise is relatively large, which is suitable for objects with relatively flat surfaces. The higher the frequency, the worse the cavitation effect, but the noise is relatively low, which is suitable for objects with many micropores and blind holes and electronic crystals. 2. Temperature dependence: Generally, the medium temperature of 30℃-50℃ has the best cleaning effect. 3. Related to sound intensity: According to different frequencies, the sound intensity is generally around 1-2w/cm2. 4. Related to cleaning solution: Generally speaking, the lower the viscosity of cleaning solution, the higher the gas content, and the better the cleaning effect. 5. It is related to the depth of the cleaning liquid and the position of the object to be cleaned. Application of ultrasonic cleaning in various fields Because ultrasonic cleaning itself has incomparable advantages over other physical cleaning or chemical cleaning, it is widely used in service industry, electronic industry, pharmaceutical industry, laboratory, machinery industry, cemented carbide industry, chemical industry and many other fields. Here is a brief introduction to individual industries. 1, service industry application. In daily production, you can use ultrasonic to clean glasses and jewelry, which is fast and harmless. Large hotels and restaurants use it to clean tableware, which not only has good cleaning effect, but also has the function of killing viruses. 2. The application of ultrasonic wave in micropowder industry is well known. In order to obtain particles of different sizes, the crushed materials are put into a ball mill for grinding and screened with screens of different specifications. If the screen is used for a long time, it will block the sieve holes (such as diamond screen), and other methods will destroy the screen and the effect is not ideal. After many manufacturers' experiments, ultrasonic cleaning will not only damage the screen, but also completely recover the blocked particles on the screen. 3. Application of ultrasonic in pharmaceutical industry Ultrasonic cleaning technology has been widely used by many pharmaceutical companies, especially for cleaning penicillin bottles, oral liquid bottles, ampoules and large infusion bottles, as well as butyl rubber plugs and natural rubber plugs. For bottle cleaning, ultrasonic cleaning technology is used to replace the original brush machine, and it is realized through the processes of overturning water injection, ultrasonic cleaning, internal and external cleaning, air drying and overturning. 4. Ultrasonic cleaning of filter element We know that no matter what kind of filter material or filter for any purpose, after a period of use, it will be scrapped due to the decrease of transmittance caused by impurities. The price of ordinary filter elements is ok, but for the chemical fiber industry, an imported filter element costs nearly 10 thousand yuan, which is a pity to abandon. The ultrasonic filter cleaner developed by us in cooperation with other scientific research units adopts a special-shaped ultrasonic cleaner. It can concentrate energy above 1KW on the radiation surface of 200×20mm2, with high ultrasonic intensity, and can quickly remove the blockage. At the same time, the equipment adopts a filter. As long as you provide the wave core, we can provide you with a complete set of cleaning devices. (It takes 10— 15 minutes to clean the filter element in this equipment). Suitable for PP cotton filter, activated carbon filter and hollow fiber filter. 5. Ultrasonic cleaning of metal As we all know, after a metal rod is extruded into silk, there is often a carbonized film and oil on the outside of the silk. It is difficult to remove dirt (especially the whole line) by pickling or other cleaning methods. Ultrasonic wire washing machine is a continuous and efficient cleaning equipment designed according to the actual production needs. The rough washing part is composed of cleaning liquid storage tank, frequency converter, circulating pump, filter and supporting pipeline system, which carries out ultrasonic rough washing on wire. The integrated control of the whole set of equipment is simple, convenient and effective, and it is widely used in other metal wires such as tantalum wire, tungsten wire, molybdenum wire, niobium wire and copper wire (before coating insulating paint). 6. Application of ultrasonic cleaning technology in phosphating treatment. Pretreatment process before product spraying is very important. The traditional process generally uses acidic solution to treat the workpiece, which has great environmental pollution and poor working environment. At the same time, the biggest disadvantage is that it is difficult to rinse off the residual acid after pickling and rust removal of parts with complex structure. It is not long after the workpiece is sprayed, and corrosion occurs along the crack, which destroys the surface of the coating and seriously affects the appearance and internal quality of the product. After the ultrasonic cleaning technology is applied to the pretreatment of painting, not only can the dirt and cracks on the surface of the object be peeled off quickly, but also the sprayed layer on the painting part is firm and will not rust back. Ultrasonic cleaning can be used in all walks of life. The above are only representative industrial applications, and there are many new industries and fields that can use ultrasonic cleaning. We look forward to the development and exploration of users and manufacturers. Ultrasonic thickness measurement and its application in industrial field Ultrasonic thickness measurement is a mature high-tech technology. Its greatest advantage is that it is safe, reliable and accurate, and it can be checked in the running state. Ultrasonic thickness gauge can be divided into vibration method, interference method and pulse reflection method according to its working principle. Several kinds, because the pulse reflection method does not involve vibration mechanism and is not closely related to the surface smoothness of the measured object, the ultrasonic pulse thickness gauge is the most popular instrument for users. The working principle of 1 ultrasonic thickness gauge is mainly composed of host and probe. The host circuit includes three parts: transmitting circuit, receiving circuit and counting display circuit. The high-voltage shock wave generated by the transmitting circuit excites the probe to generate ultrasonic transmitting pulse wave. The pulse wave is reflected by the medium interface and received by the receiving circuit. After the single chip microcomputer counts, the LCD displays the thickness value. It mainly obtains the thickness of the sample according to the propagation speed of sound wave in the sample multiplied by half the time it passes through the sample. HT series ultrasonic thickness gauge produced by our factory is a pocket intelligent measuring instrument with low power consumption and low lower limit based on advanced technology at home and abroad and developed by single chip microcomputer technology. There are not only instruments for measuring the thickness of different materials, but also single steel and ultra-thin ones, all of which can be equipped with high-temperature thickness measuring probes. 2 Application field of thickness gauge Because ultrasonic processing is convenient and directional, ultrasonic technology has the advantages of rapidity, accuracy and no pollution, especially when only one side can be touched. It is widely used in various plates, pipes, boiler vessels and their local corrosion and rust, so it is very important for metallurgy, shipbuilding, machinery, chemical industry, electric power, atomic energy and other industries. Ultrasonic cleaning and ultrasonic thickness gauge are only part of the application of ultrasonic technology, which can be applied in many fields. Such as ultrasonic atomization, ultrasonic welding, ultrasonic drilling, ultrasonic grinding, ultrasonic polishing, ultrasonic motors, etc. Ultrasonic technology will be more and more widely used in all walks of life. The application of infrasound began in the 1950s, and gradually attracted people's attention. The application prospect of infrasound is as follows: (1) By studying the characteristics and mechanism of infrasound produced by natural phenomena, we can deeply study and understand the characteristics and laws of these natural phenomena. For example, infrasound generated by aurora can be used to study the law of aurora activity. (2) Using the received infrasound generated by the measured sound source, the position and size of the sound source can be detected and other characteristics can be studied. For example, by receiving infrasound generated by nuclear explosion, rocket launch or typhoon, the relevant parameters of these infrasound sources can be detected. (3) Predicting natural disasters. Many disastrous natural phenomena, such as volcanic eruption, tornado, thunderstorm, typhoon, etc. Infrasound may be radiated before they occur, so it is possible for people to use these precursor phenomena to predict and predict the occurrence of these disastrous natural events. (4) Infrasound is easily influenced by atmospheric media when it propagates in the atmosphere, which is closely related to factors such as wind and temperature distribution in the atmosphere. Therefore, by measuring the propagation characteristics of naturally or artificially generated infrasound in the atmosphere, some large-scale meteorological properties and laws can be detected. The advantage of this method is that it can continuously detect and monitor a large range of atmosphere. (5) By measuring the results of the interaction between infrasound and other fluctuations in the atmosphere, these activity characteristics are detected. For example, the propagation of radio waves is disturbed by infrasound in the ionosphere, and the law of ionospheric disturbance can be further revealed by measuring the characteristics of infrasound. (6) People and other creatures can not only respond to infrasound, but also some of their organs can emit weak infrasound. Therefore, we can use the characteristics of these infrasound waves to understand the activities of the corresponding organs of human body or other organisms.

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