RU2844367C1 - Method of protecting fry of valuable fish species in open basins from birds of prey - Google Patents

Abstract

FIELD: fish farming; scaring of animals.

SUBSTANCE: invention relates to fish farming and can be used to scare birds away over ponds with fry. Method is characterized by the fact that air space above a reservoir with fish fry is irradiated with ultrasonic radiation pulses with frequency of 30 kHz. Frequency of switching on pulses F_mod is set in range of 1-20 Hz, and duration of pulses Δt_mod is determined from inequality Δt_mod≤0.5/F_mod.

EFFECT: invention provides protection of fry of valuable fish species in open basins from birds of prey.

1 cl, 3 dwg, 3 tbl

Description

A method is proposed for protecting fry of valuable fish species in open pools from birds of prey by creating conditions that repel birds when they approach and are in the pool area.

It is known [1,2] that all living beings with a circulatory system have mechanical vibrations and resonances of organs. Resonances of most creatures are observed in the range of infrasound vibrations in the range of 1.0-20 Hz. These vibrations, being adequate stimuli for the receptors of organs and balance, easily cause motion sickness or fear, balance. Infrasound usually has a negative effect on humans. Depressed state, fatigue and at medium radiation intensity 140 dB may cause fainting, loss of vision. At an intensity 180 dB can cause paralysis or death.

Analyzing physical studies of the structure of organs and tissues, determining their elasticity and resonance frequencies, and assessing the functional state of a person, the authors believe that infrasound vibrations will have a similar effect on birds (in work [1], a chicken is used as an example).

In accordance with the law on weapons (see paragraph 7 of clause 1 of article 1), restrictions on the use of electromagnetic, light, thermal and ultrasonic radiation can be ignored since the proposed method eliminates contact of radiation with a person, since it is directed upward, where it is absorbed by the atmosphere.

The disadvantage of any infrasound emitter (the authors consider them as analogs) is the need to comply with the requirements for the correspondence of the geometric dimensions of the emitter to the wavelength of the radiation. For a frequency of 1.0 ÷ 20.0 Hz, the wavelength is 340 m and 17 m at a sound speed of 340 m/s.

Thus, the technical result of the proposed method is the elimination of the shortcomings of analogues.

A method is proposed for protecting young fish of valuable species in open pools from predatory birds, which consists in irradiating the air space above the reservoir with young fish with ultrasonic (US) radiation pulses with a frequency of 30-40 kHz, while the frequency of switching on the US pulses set in the range of 1-20 Hz, and the pulse duration determined from the inequality

Thus, a method is proposed that uses the so-called radiation pressure of ultrasonic radiation in the infrasonic range. This mechanism is described in sufficient detail in the works [3,4,5] and relates to second-order sound effects. It consists in the fact that the surface of an obstacle in the path of radiation experiences a pressure of constant magnitude and direction similar to light pressure. These works show that the radiation pressure is 10 ² -10 ³ times less than the sound pressure.

The essence of the method is explained by the following materials: Fig. 1-1a - shows a narrow pool with ultrasonic emitters on rods on its banks, where 1 is an ultrasonic emitter with a visor 2, 3 is a rod, 4 is an irradiation zone, the angle between the axis of the radiator's radiation pattern and the horizon line is 5, the angle of the emitter's "swing" along the horizon; 1b - shows a wide pool in which the ultrasonic emitters on rods are located in the water above the area where the fry are concentrated; Fig. 2 - a functional diagram implementing the proposed method and its operation diagram, where 7 is an electric generator for the ultrasonic frequency, 8 is a modulator for the frequency with external control, 9 - emitter.

Radiation pressure causes pain in humans, which has been confirmed experimentally in [3,4]. The studies have shown that at a sound intensity in the air 1 W/ ^cm2 (160 dB) sound pressure is ^3⋅103 Pa, and radiation pressure is 3 Pa. Also indicated are the resonant frequencies of human internal organs, the performance of which is affected by radiation. At the same time, the types of changes in the mental state of a person who finds himself in the radiation field are indicated:

- heart rate reduction - 1÷2 Hz

- fear, disturbance of peace

(coincides with delta rhythms of the brain) - 8÷13 Hz

- mental impairment

(coincides with beta rhythms of the brain) - 14÷20 Hz

- dizziness - 12 Hz

- anxiety, fear - 15-18 Hz

The use of ultrasound radiation is explained by the following circumstances:

- in the ultrasonic range it is possible to achieve higher values of radiating power,

- in the ultrasonic range, the overall dimensions of the emitters are significantly reduced at low (no more than 100 V) supply voltage of the elements.

Ultrasonic emitters implement mechanical vibrations by radiation elements, which significantly increases the amplitude of vibration at resonant frequencies. In the ultrasound field, materials with a piezoelectric effect are used. Such plates are polarized by thickness Δ, and the maximum radiation efficiency is achieved when Δ is equal to the half-wavelength of the radiation. So, when

Also, materials with a piezoelectric effect have high permissible values of operating temperatures (above +300°C). Ultrasonic emitters with a power of 5-10 W/ ^cm2 have an efficiency of about 30%, which is almost an order of magnitude higher than the efficiency of emitters in the sound and infrasound frequency ranges.

Let's calculate the sound pressure value with two values radiation intensities of 5 W/ ^cm2 and 10 W/ ^cm2 according to the known relationship

v

acoustic resistance of air, as a result of which we obtain

Let's average the sound pressure reduction factor and take it equal to 5⋅10 ² times. Then the radiation pressure at the specified intensity will be

It follows from the table that the losses of ultrasonic radiation in the frequency range of 30-60 kHz are equal to 120 dB/km and 400 dB/km, respectively. The table shows the values of ultrasonic radiation losses at lengths of 10 m, 50 m, 100 m and 200 m.

The results of ultrasonic radiation losses allow us to draw the following conclusions on the proposed method:

- to implement the method, it is advisable to use frequencies of 30-35 kHz;

- it is advisable to establish the length of the ultrasonic radiation path according to its purpose.

Fig. 1 shows the locations of the ultrasonic emitters that cause fear in birds and make it impossible to stay in the radiation zone. Fig. 2 shows a functional diagram implementing the proposed method. Ultrasonic electric signals from generator 6 are fed to modulator 7 with manual setting of ultrasonic pulses at a frequency of 1-20 Hz with a duty cycle of 2, the pulses are directed to emitter 9. Experimental adjustment of the ultrasonic equipment involves on-site refinement of the frequency selection , and the exposure time for this type of bird. Angle 5 The authors recommend setting it equal to 20 degrees, which at a distance of 20 m provides a beam lift of 11 m. Swing angle It is also recommended to set ±20 degrees along the horizon line, which at a distance of 20 m ensures scanning over an area of 22 m.

The authors note the wide possibility of practical use of the proposed method:

- to protect street monuments from birds shown in Fig. 3;

- for zoos and veterinary services when calming down enraged animals,

- to "calm down" a raging, uncontrollable crowd of hooligans

- for hunters,

- at airports to disperse birds.

The use of this method in an aquatic environment is interesting.

The authors believe that the proposed method can find wide application in Russia and other countries.

Literature

1. E.E. Faustova, A.B. Timofeev, G.A. Timofeev, V.N. Fedorov “Mechanical vibrations and resonances in the human body” - M.: Fizmatliterature, 2006.

2. Yu. A. Krutyakov (patent holder), M. A. Gorbunov, A. Yu. Kachalov, S. S. Shavrin “Method of protecting a closed space from unauthorized entry”, Russian Federation patent No. 2540783 dated 01.04.2013.

3. A.M. Prokhorov (editor) “Physical Encyclopedia” - M.: Nauka 1970

4. A.E. Kolesnikov “Ultrasound measurements” - M.: Science, 1970.

5. Handbook "Acoustics" - M.: Radio and Communications, 1989.

6. N.P. Koshkin, M.G. Sharkevich Handbook of Elementary Physics - M.: Nauka 1985.

7. I.A. Aldoshin et al. “Electroacoustics and sound broadcasting” - M.: Radio and communication, 2010.

8. Ultrasonic equipment PSB-Gals, psb-gals.ru

Claims (1)

A method for protecting young fish of valuable species in open pools from birds of prey, characterized by the fact that the air space above the reservoir with young fish is irradiated with ultrasonic radiation pulses with a frequency of 30 kHz, while the pulse switching frequency set in the range of 1-20 Hz, and the pulse duration determined from the inequality .