The effects of elastic waves on biological objects elastic waves in nature, science, engineering, technology, medicine

Electrodeposition is a process in which the deposited metal becomes finely crystalline and its porosity is reduced. In this way copper plating, tinning and silvering are carried out. The process is faster and the quality of the coating is higher than in conventional techniques [111].
Drying is carried out without heating of biologically active substances, in the food, pharmaceutical industry.
Spray drying of liquids and melts. Intensification of processes in spray dryers. Obtaining metal powders from melts. These spraying devices eliminate rotating and rubbing parts.
Ultrasonic boosts the combustion efficiency of liquid and solid fuels by a factor of 20.
Impregnation. Hundreds of times faster through the capillaries of the material to be impregnated. Used in the production of roofing felt, sleepers, cement boards, textolite, gethinax, wood impregnation with modified resins.
6. Ultrasonic welding in metallurgy. Metals are known to absorb gases from aluminium and its alloys during melting. 80% of all gases in the molten metal account for H₂ . This leads to deterioration of metal quality. Gases can be removed by ultrasonic removal, which allowed in our country to create a special technological cycle and widely used in metal production.
US aids in the hardening of metals. In powder metallurgy, ultrasonic welding promotes the adhesion of the particles of the material to be made. This eliminates the need for high-pressure sealing.
7. Ultrasound in mining. The application of ultrasound allows the following technologies to be implemented:
- removal of paraffin from the walls of oil wells;
- avoiding methane explosions in mines by dispersing methane;
- The ultrasonic method in ore beneficiation (ultrasonic flotation method).
8. Ultrasonic vibrations in agriculture. Ultrasonic vibrations have a beneficial effect on seeds and grains before planting. Thus, treatment of tomato seeds before planting provides an increase in the number of fruits, reduces the ripening time and increases the amount of vitamins. US treatment of melon and maize seeds increases yields by 40%. The ultrasonic seed treatment can provide disinfection and introduce the necessary micronutrients from the liquid.
9. Food industry. The following technologies are already being implemented in practice today:
- processing of milk for homogenisation, sterilisation;
- treatment to increase the shelf life and quality of frozen milk;
- to produce high quality milk powder;
- the production of emulsions for baking;
- treatment of the yeast increases its fermenting power by 15 %;
- obtaining aromatics, mash, extracting fat from the liver;
- the isolation of the tartar;
- extraction of vegetable and animal raw materials;
- perfume production (6...8 hours instead of a year).
10. Ultrasonic in biology. Large doses of ultrasound kill micro-organisms
(staphylococci, streptococci, viruses); low-intensity ultrasound exposure promotes the growth of microbial colonies.
11. The effect of ultrasound on humans. Ultrasound exposure with intensities up to 0.1-0.4 W/cm² is therapeutic. In America, exposure to intensities of up to 0.8 W/cm is considered therapeutic² .
12. Ultrasound in medicine. Ultrasonic scalpels, devices for external and internal liposuction, laparoscopic instruments, inhalers, massagers find the widest application and allow the treatment of various diseases [111].
2.5 Application of ultrasound in agriculture

Preplanting ultrasonic treatment of grains and seeds intensifies the germination process and increases the yield of various crops by an average of 20-40% [128-134]. For example, ultrasound-treated barley grains sprout 2-3 days earlier than the control planting, the ear length and number of grains in it are increased by 30%, the number of stems from one grain is also increased by 25-30%. The mechanism of ultrasound effect on grains and seeds is not fully investigated. What is clear is that ultrasound can stimulate the vital forces laid down by nature in every crop. Experimental studies have shown that ultrasound exposure to a greater or lesser extent, but always has a positive effect on the process of germination of grains and seeds and increases yields. The maximum increase in yield was noted in melons - by 46%. Treatment of cucumber seeds before planting leads to the fact that the internodes on the adult plant (fruit formation places) are formed one and a half times more often, the resulting fruits differ from the control with better taste. The treatment of tomato seeds with ultrasound revealed that after planting, the bushes grew stronger, more fruits were formed, and they ripened faster than the controls. Analysis of fruit composition showed that the ultrasound-treated tomatoes had more vitamins than the controls. Good results were obtained by ultrasound treatment of cabbage, carrot, beetroot and onion seeds. The treatment of seeds with ultrasound can introduce the necessary microelements, destroy pathogens and pests, activate enzymes. For example, treatment of radish seeds with ultrasound in the solution of organic fertilizers increases the yield by less than 2 times. The following must be taken into account when treating grains and seeds with ultrasonic treatment. Treatment of seeds and grains can be carried out in water or in an aqueous solution of trace elements and fertilizers. Usually an aqueous solution of potassium permanganate is used as such a solution. A change in the color of the aqueous potassium permanganate solution from pink to light yellow can be an indication that the treatment is sufficient. When treating seeds in small glass volumes (less than 200 ml), the treatment time should be reduced to 3 min. When treating grain in larger volumes (e.g. in three-litre jars), it is allowed to treat up to 1 kg of grain, ensuring that it is agitated. In this case the treatment time is 20 min and the grain is stirred every 1-2 min. The phytomixer can be used to prepare fertilizer solutions and extracts, including disinfectant extracts [111, 128-134].

2.6 Ultrasonic drying unit

Ultrasonic drying of fibrous materials can partially compensate a number of disadvantages of thermal drying, in particular the high energy consumption of the process. The speed of the ultrasonic drying process is determined by a complex of factors [135, 136-140]: acoustic currents, micro currents near obstacles, radiation pressure, and cavitation. The energy intensity of the process is reduced by removing part of the moisture by atomization, bypassing the evaporation process. There are two different approaches for realizing the drying process: the introduction of vibrations through the air medium and the direct introduction of vibrations into the material to be dried [141-146].

The method of direct exposure to vibrations through the material to be dried is effective for drying sheet materials, while the exposure through the air medium is effective for bulk materials. The limited penetration of ultrasonic drying to date is due to the imperfection of devices for generating ultrasonic vibrations in airborne media.
A small-scale batch-type drum dryer for drying various fibrous materials was developed and manufactured for the purpose of research. A diagram of the dryer is shown in figure 2.11.
The dryer consists of the outer casing 1 covered with a layer of sound-absorbing material 8; drying drum 2; outer drum 3 covered with a layer of sound-absorbing material 9; rotation drive of drying drum 4; heating and circulation of drying agent (air) 5; acoustic radiator 6; installed in the door of the dryer hatch 7; located in the open end part of drum 2. Basic parameters of the dryer are presented in Table 2.4.
An electroacoustic system comprising an electronic oscillator and an acoustic radiator is used as the source of the ultrasonic vibrations. When radiated at all points inside the drum, the intensity level of the ultrasonic vibrations was found to be at least 135 dB, near the radiator the intensity level of the vibrations was found to be between 140-160 dB.



Figure 2.11 - Design of the compact drum dryer
Table 2.4 - Basic parameters of the created drum dryer

№	Parameter name	Unit of measure
1	Drum volume, l	60
2	Filling ratio, max.	0,5
3	Tumbling the material	drum rotation
4	Drying agent	air
5	Drying agent temperature, ^oC, max.	120
6	Heater output, kW, max.	2
7	Power of ultrasonic vibrations introduced into the drying chamber, kW, max.	0,35

In this case the reflection of ultrasonic vibrations from the drum walls contributed to the formation of local additional foci, located at points distant from the acoustic axis of the radiator [135, 147-151].

Figure 2.12 shows the construction of the ultrasonic radiator. The transmitter is mounted in the manhole cover 1 of the dryer drum. An acoustic decoupling unit 2 prevents the transmission of vibrations from the transmitter to the manhole cover. The transmitter itself is formed by a piezoelectric ultrasonic oscillating system 3, which excites the oscillations of the radiating disc 4.
The ultrasonic acoustic radiator was powered from an electronic generator in which the technological apparatus control method proposed in this work was implemented on the basis of matching the parameters of electroacoustic system components and technological environment. The use of an outer drum surrounding the drum for the dried material, as well as sound-absorbing materials allowed to reduce the level of acoustic radiation outside the dryer to a safe level of 80 dB at a distance of one meter from the housing.

1-Cover; 2-Acoustic decoupling unit; 3-Instrument oscillation system; 4-Encitation oscillations of the emitting disc
Figure 2.12 - Acoustic transducer design

Cotton fiber was used as a drying object in the pilot study, and its wide range of possible variations in moisture content made it possible to simulate the drying process of materials with different moisture contents. In addition, determining the moisture content of fibrous material in an experiment by weight measurement is easier than determining the moisture content of bulk materials. In a process study, the moisture content of the material to be dried was determined using the formula:

(2.1)
where M_В is the mass of a wet material sample, kg; M_С is the mass of a dry material sample, kg.
In the course of investigation the dependencies of speed and specific energy intensity of drying process of fibrous materials on volume density of energy of acoustic vibrations, introduced into the drying chamber, at various temperatures of drying air were determined. In figure 2.13 dependencies corresponding to the first period of drying (moisture content 70 %) are presented. Figure 2.14 shows the dependencies corresponding to the second drying period (moisture content 10 %). To maintain a drying air temperature of 120^o C in the drying chamber, a heater output of 34 kW/m³ and to maintain a drying air temperature of 60^o C, 14 kW/m³ were required. The drying air temperature of 20^o C was maintained without a heater [136, 154-157].




Figure 2.13 - Rate dependence (a) and specific energy consumption (b) of the ultrasonic drying process of cotton fiber at 70% moisture content and different drying air temperatures

Figure 2.14 - Rate dependence (a) and specific energy consumption (b) of the ultrasonic drying process of cotton fibre at 10 % moisture content and different drying air temperatures

The analysis of the data obtained shows that in order to achieve the highest efficiency of the drying process, the maximum possible ultrasonic vibration energy must be introduced during the first period, whereas no ultrasonic vibration exposure is required during the second period. Since the most rapid changes in the properties (temperature, humidity) of the technological medium (drying air) occur precisely at the beginning of the drying process, the maximum possible (for the electroacoustic system used) ultrasonic vibration energy input into the drying chamber requires adjustment of the electroacoustic system parameters to ensure optimum agreement with the technological medium [135, 156-162].

Figure 2.15 shows the drying kinetics of 1 kg of cotton fibre from a moisture content of 70 to 5%.



Figure 2.15 - Drying kinetics of cotton fiber at drying air temperatures of 120^o C (a) and 60^o C (b)

Drying was carried out in the created dryer with application of various sources of energy of ultrasonic vibrations, and also without application of ultrasonic vibrations (convective drying) at temperature of drying air of 120 and 60^o С. Diagram "SP1" corresponds to the vibration input by electroacoustic system (EAS №1) that does not take into account the influence of technological medium properties on the mode of transformation and input of ultrasonic vibrations. Graphic "US2" corresponds to the vibration input by electroacoustic system (EAS No. 2), in which the effect of changes in the properties of technological medium on the mode of transformation and input of vibration energy is taken into account and compensated according to the proposed method of control of technological device's operation. In table 2.5 the basic parameters of process of drying of cotton fibre, received during experiment are presented.

Thus, in the course of this experimental study it was found that the efficiency of the ultrasonic drying process can be improved by improving the ultrasonic vibration energy sources based on matching the parameters of the EAS components and technological media [135].

Table 2.5 - Main indicators of the cotton fibre drying process obtained during the experiment

Source of KM oscillations	Air temperature 120^o C		Air temperature 60^o C
	Drying time, min	Spent energy, MJ	Drying time, min	Spent energy, MJ
EAS NO. 1	55	7,3	103	6,5
EAS NO. 2	47	6,7	87	6,1
Without UZ	65	7,8	142	7,0

2.7 Effects of elastic waves on insects