2. Ultrasonic treatment. The use of ultrasound mechanical action, cavitation, thermal and chemical effects, can be ultrasonic welding, drilling, crushing of solids, emulsification, degassing, dust, pot scale, cleaning, sterilization, chemical reactions and biological research, etc., in the industrial and mining industry, agriculture, medical and other sectors to obtain a wide range of applications.
3. Basic research. Ultrasonic action in the medium, in the medium to produce acoustic relaxation process, acoustic relaxation process is accompanied by energy in the molecules of the respective degree of transport between the transport process, and in the macroscopic performance of acoustic absorption (see acoustic wave). The properties and structure of matter can be explored by means of the absorption patterns of ultrasound, and research in this area constitutes the branch of acoustics known as molecular acoustics. The wavelength of ordinary sound waves is much larger than the atomic spacing in solids, which can be treated as a continuous medium under these conditions. However, for special ultrasonic waves with frequencies above 1012 Hz, the wavelengths are comparable to the spacing of atoms in a solid, which must be treated as a spatially periodic array of points. The energy of the dot matrix vibrations is quantized and is called a phonon (see physics of solids). The action of ultrasound on solids can be summarized as the interaction of ultrasound with thermal phonons, electrons, photons, and various quasiparticles. The study of the laws of generation, detection, and propagation of ultrasound in solids, as well as the study of acoustic phenomena in a quantum liquid, liquid helium, constitutes a new field of modern acoustics-
2 Applications of ultrasound in agriculture
2.1 Ultrasonic treatment and processing of the basic principles
Ultrasonic treatment and processing equipment is mainly composed of four parts: ultrasonic generator, transducer, ultrasonic concentrator and ultrasonic generator and transducer between the matching circuit. As shown in Figure 1, the ultrasonic generator produces a certain high-frequency electrical energy provided to the ultrasonic transducer, the ultrasonic transducer will be converted into mechanical energy, and then through the ultrasonic polymerizer to amplify the mechanical energy, the acoustic energy in the material to be treated. Ultrasound biological effects are widely used, the main biological effects are derived from the cavitation caused by mechanical and thermal effects. The basic principle of ultrasonic treatment and processing is to use the cavitation phenomenon of liquid dynamics. Ultrasonic cavitation refers to the ultrasonic activation of various dynamic manifestations of the bubble, these manifestations may be more regular and gentle steady state cavitation or very intense and short transient cavitation. Transient cavitation bubble adiabatic contraction to the collapse of the moment, the bubble can be high temperature and high pressure of several thousand atmospheres, accompanied by powerful shock waves or jets. The mechanical effects of ultrasonic irradiation can enhance the motion of the mass of the liquid medium, accelerate mass transport, and affect the boundary layer, membranes, cell walls and vesicles. The cavitation effect of ultrasound also destroys cells and denatures enzymes. The following examples of new applications of ultrasound in agriculture are basically based on the above basic principles and realize.
2.2 Ultrasonic determination of lead in soil[1]
Lead is a harmful element, which is commonly measured in soil analysis. When using the suspension of direct injection flame atomic absorption spectrometry for the determination of lead in soil, due to the large amount of soil samples, the suspension of the viscosity of the emulsion, not easy to disperse uniformly and affect the shortcomings of the injection. The method of treating the suspension with ultrasonic waves first and then injecting the sample can make the injection smooth and prolong the stabilization time of the suspension; the sensitization of sodium dodecyl sulfate (SDS) can improve the sensitivity of direct injection of suspension for the determination of lead in soil by flame atomic absorption spectrometry (AAS). The method is rapid, simple, accurate and suitable for the determination of lead in various soil samples.
2.3 Ultrasonic treatment of seeds
Ultrasonic breeding, the application of ultrasonic treatment of seeds, as early as in the former Soviet Union has been a lot of research. According to foreign literature, a small amount of ultrasound can stimulate cell division, a moderate amount of ultrasound will inhibit cell division, a large number of can cause cell death. In the last century, ultrasound was used in experiments on spinach and cabbage seeds. The results of these experiments showed that when cabbage seeds were treated with ultrasound for 1 minute and 2 minutes, the germination rate of the seeds was 92%-96%, while the germination rate of cabbage seeds without ultrasound treatment was 88%. In the case of spinach seeds treated with ultrasound for 1 minute, the emergence rate was 85%, while the emergence rate of spinach seeds not treated with ultrasound was 40%[2] . The increase in yield of ultrasonically treated seeds was also significant at a later stage. Low frequency pulsed ultrasound was found to have a significant effect on the variation of wheat seedlings. The emergence rate of hydroponically grown mutant seedlings irradiated with ultrasound was 8.57±8.25%, compared with 1.00±1.28% of natural variation in the control; the emergence rate of field-grown mutant seedlings was 18.21±2.54%, compared with 14.58±2.59% of natural variation in the control. The grain weight of irradiated HANNONG 68 wheat exceeded that of its parents in 55.17% of the lines, and 87.50% of the irradiated lines exceeded that of their parents by a significant level of 1%. In irradiated tetragonal wheat, the grain weight of single plant exceeded that of the parental lines by 69.23%, and 77.78% of the superparental lines reached the 1% significant level[3] .
2.4 Effect of ultrasonic treatment on plant growth
Ultrasonic seedling cultivation, like other environmental stresses, ultrasound as a form of stress, has an important effect on plant growth and development. In recent years, under ultrasonic treatment, from the macroscopic observation of changes in plant growth to the study of plant physiology and biochemistry, from the study of the impact of plant cells, tissues, division and growth to the ultrasonic treatment of the role of the mechanism of the plant, have achieved a lot of results. Ultrasonic treatment can affect the survival and growth of plants or certain organs. Studies on organ growth have focused on roots, and mild ultrasonication has been shown to promote rooting[4] . Plant cells treated with ultrasound showed a consistent phenomenon, i.e., mild treatment at low doses for a short period of time significantly accelerated and induced plant cell division, stimulated cell growth, and accelerated protein synthesis in protoplasts; whereas prolonged treatment time and increased treatment dose caused negative and irreversible effects. Ultrasonic treatment of preservation solution can delay the onset of fresh weight decline, increase the maximum stem size, and prolong the life of flower arrangements[5,6] . It can be seen that a certain frequency and intensity of ultrasonic treatment can strengthen some physiological and biochemical indicators of plants, and promote the growth and development of plants.
2.5 The effect of ultrasonic treatment on plant respiration
The study of plant respiration has always been a hot spot in the study of plant physiology, especially for crops, the size of its respiration is directly related to the level of yield, so its study of the development of agriculture is of great theoretical and practical significance. 1975 Albu E found that low frequency of In 1975, Albu E found that after treating vegetables with low frequency ultrasound (25kHz), the respiration intensity of annual plants (e.g., tomato and cucumber) decreased, while the respiration intensity of biennial plants (e.g., cabbage and onion) increased[7] . From this we can hypothesize that the use of ultrasound to treat the crops in question can increase the yield of the crops.
2.6 Ultrasonic plowing
The traditional tilling plows need to be pulled by bulky machines, which not only compacts the deeper soil and prevents it from retaining water and nutrients; but also the upturned surface soil is eroded by wind and rain. This is a major problem for many farmers. In addition, because of the many plowing operations, plant roots and decaying plant residues are turned up from the surface, where they give off carbon dioxide gas. Naida Abulhad, a Jordanian agricultural engineer, invented the use of ultrasound to loosen the soil. His experiments showed that the soil could be loosened up to a depth of 20 cm. This is the exact depth of loosening for normal crops.
2.7 Ultrasonic treatment of plant roots[8]
Sugars are one of the main components of the plant body, and soluble sugars mainly refer to monosaccharides and oligosaccharides. The content of phosphate monosaccharides in plant cells is not high, but they are the main intermediate products in the process of photosynthesis and respiration, which are very important in the metabolic process. After ultrasonic stimulation, the content of soluble sugars in the root system was about 29.6% higher than that of the control. Abundant protein is the material basis for a series of physiological activities of the cells, after ultrasonic stimulation, the soluble protein in the root system increased by 35.3%, the high level of soluble protein content ensures the cell division and growth ability, which indicates that after ultrasonic stimulation, the plant root cell division is vigorous and the growth ability is strong.
2.8 Ultrasonic de-worming[9] and promote the hatching of silkworm eggs
With 250W-CFS ultrasonic generator (Central Plains Electronic Instrumentation Factory) matched with its own cleaning tank, the fruit of the chestnut has been born with worms immersed in the cleaning tank in the tap water, at 19.5 ~ 20.5kHz, the boot processing 15min, the end of the water drying, preserved. After that, the chestnuts were dried and stored for 2 weeks. When the chestnut fruit was cut open and examined, the larvae about 10 mm in length were still alive, while the larvae less than 6 mm in length died. The mortality rate of the worms was almost the same when the treatment time was increased. In addition, some people have used similar methods and equipment to treat silkworm eggs (within about half a minute), and as a direct result, the hatching time of antworms reached the same level; the tracing result was an increase in the extraction rate of cocoons made from adult silkworms grown up under the same conditions. There have also been attempts to use ultrasound to treat pests in fruits (apples, pears, etc.), but most of them were fruitless.
2.9 ultrasonic catalytic
3. Ultrasonic applications in industry
Ultrasonic level level meter
Ultrasonic flow meter
Ultrasonic flaw detector
Ultrasonic limit switches
Ultrasonic cleaning device
Applications
Industry categories Electronic and electrical
Instrument industrial machinery Optical machinery, treasure
Stone processing, watch industry Automobile, motor
To car industry Chemical fiber textile food
Brewing Aviation, aircraft industry
4. Ultrasonic applications in the military
Sonic weapons
General belief that the sound and the auditory sense is linked together, but it as a kind of air wave Recently, U.S. Technologies Inc. in San Diego, California, has developed a gun that uses sound waves as bullets.
Active sonar: the same basic principle as a bat's pathfinder.
Active sonar.