RU2540783C2 - Method of protecting closed premises in case of intrusion - Google Patents

Abstract

FIELD: physics, signalling.

SUBSTANCE: disclosed is a method of creating unbearable mental conditions for intruders in closed premises (offices, banks, cars etc.), fitted with special-purpose locking devices. Said conditions are created by automatically turning on an ultrasonic generator, the radiation of which is directed into the interior of the premises. The ultrasonic radiation is modulated with rectangular pulses with modulation frequency of 1 Hz or higher. The pulse ratio of the ultrasonic radiation is set equal to 2. The resultant radiation pressure is equivalent to infrasound radiation. Parameters of the ultrasonic radiation and reverberation time are associated with parameters of the premises, particularly with the size and coefficient of reflection of the sound wave by walls of the premises.

EFFECT: providing higher radiation power while reducing overall dimensions of the radiator.

2 dwg, 1 tbl

Description

A method is proposed for protecting a closed room in case of unauthorized entry into it by creating conditions for the psychic impossibility of a person staying in these conditions, which can be in demand when protecting household and specific rooms.

It is well known from the media that undesirable persons entered banking and office premises in order to steal trade secrets, criminal cases, bank documents and other classified information, as well as into car dealerships for the purpose of hijacking them. This indicates that the secrets of the locking security devices are known to interested parties. Therefore, the creation of conditions for the mental impossibility of unwanted persons to stay in the room where they entered unauthorized, and their inability to realize their goals in these conditions is an urgent task today.

It is known [1, 2, 3, 4, 5] that infra-low sound waves in the frequency range from 1 Hz to 18 Hz with a sufficient intensity of these emissions are considered as a serious weapon against a person, namely:

- can cause a feeling of fear and panic, heart failure is possible;

- the most dangerous frequency of 7 Hz coincides with the frequency of α-waves of the brain and can lead to death;

- the work of many internal organs of a person occurs with a certain frequency, which is infralow, which explains the undesirable consequences of exposure to sound vibrations of this frequency on a person.

Permissible power levels with constant infrasonic exposure are 105 dB in octave bands with a frequency of 2, 4, 8, 16 Hz and 102 dB in an octave band of 31.5 Hz. In the case of inconsistent infrasound exposure, the aforementioned general levels are normalized (in particular, the duty cycle is taken into account in the case of a periodic pulsed exposure regime).

In the Russian Federation, the Law “On Weapons” is in force, which, in accordance with paragraph 7 of clause 1 of Article 6, states: “... the circulation of weapons and other devices, the damaging effect of which is based on the use of electromagnetic, light, thermal, infrasound and ultrasonic radiation, which "have output parameters that exceed the values established by the standards of the Russian Federation and correspond to the norms of the Federal Executive Body in the field of healthcare." Permissible power values for infrasound are indicated above.

The proposed method of protecting a closed room in case of unauthorized entry into it is based on the use of exposure to infrasound radiation. Given the above limitations, the technical solution of the method is to create in a closed room conditions of mental impossibility of people staying there without inflicting injury on them that may occur when using forbidden radiation power levels (for infrasound no more than 130-140 dB).

In technical essence, the well-known method of intermittent exposure to infrasound in the law "On Weapons", as well as in [2, 3, 5], can be adopted as an analogue of the proposed method.

The disadvantage of the analogue under the direct influence of infrasound is the need to comply with the requirements of conformity of the geometric dimensions of the emitter to the wavelength of infrasound.

The proposed method eliminates the disadvantage of an analogue and prevents unwanted persons from being in a secure room when they enter it through an entrance door (s) equipped with a special locking device. The method proposes to additionally equip the entrance door (s), window (a) and ventilation hatches with security sensors, which, when unauthorized entry through the mentioned room elements through a delay time t _ass ≤15 s, include an ultrasonic (ultrasonic) oscillator operating continuously at a fixed frequency above 30 kHz and which through a modulator is connected to an ultrasonic emitter (s) of oscillations directed (s) inside the room. Moreover, the inclusion of the ultrasonic emitter is carried out by rectangular pulses with a duration of t _modes and a modulation frequency of t _modes in the range from 1 Hz and above, while the duty cycle of the inclusion of the ultrasonic emitter is set from the condition

$$\frac{\mathrm{one}}{F_{m\mathrm{about}d}\cdot t_{m\mathrm{about}d}}=2,0\pm 0,2,(\mathrm{one})$$

reverberation time T _{roar of} ultrasonic radiation at the end of t _{mod is} set from the condition

$$T_{Re\mathrm{at}}\le \frac{0,25}{F_{m\mathrm{about}d}},(2)$$

and the reflection coefficient of ultrasonic radiation from the walls of a closed room is determined from the equality

$${(\alpha )}^{n_{\mathrm{about}tR}}=\Delta P_{\min },(3)$$

- среднее число отражений в помещении, l_ср - средняя длина пути УЗ волны между отражениями, C_зв - скорость звука в воздухе, ΔP_min - минимальный уровень спада исходной единицы измерения (давления, мощности) в конце времени T_рев.Where $$n_{\mathrm{about}tR}=\frac{T_{Re\mathrm{at}}\cdot C_{s\mathrm{at}}}{l_{\mathrm{from}R}}$$

- the average number of reflections in the room, l _cf - the average path length of the ultrasonic wave between reflections, C _Sv - the speed of sound in air, ΔP _min - the minimum level of decline of the original unit of measurement (pressure, power) at the end of time T _roar .

The essence of the proposed method is illustrated by the following drawings:

figure 1 is a functional diagram of a device that implements the proposed method, where 1 - security sensors on the elements of the room (front door, window, etc.), 2 - ultrasonic generator, 3 - modulator, 4 - ultrasonic emitter, 5 - switch of the ultrasonic generator ;

 figure 2 is a timing diagram of work.

The method, as follows from its description and the FIGS. 1 and 2, based on the use of the so-called radiation pressure of sound. The mechanism of radiation pressure is considered in sufficient detail in [6, 7, 8] and relates to second-order sound effects.

Sound pressure (a first-order phenomenon) is an alternation of compressions and rarefactions in the air, and the amplitudes of compression and rarefaction are always equal. Therefore, sound pressure does not create a constant (in direction) force in the air at the surface of obstacles.

The radiation pressure of sound is expressed in the fact that the surface of an obstacle in the path of a sound wave experiences a pressure constant in magnitude and direction, which is similar to the light pressure discovered by P.N. Lebedev in 1903

The authors agree with the physical interpretation of the phenomenon of radiation pressure [8], which is associated with phenomena in which the resistance to the motion of particles of the medium will be less when the particles move from the compression region to the rarefaction region than in the case when the particles move from the rarefaction region to the compression region. It is this difference in the resistance of the medium that creates a constant pressure in the direction of sound propagation, and, as shown in the indicated papers, the radiation pressure is 10 ² ÷ 10 ³ times less than the sound pressure.

The proposal to use ultrasound radiation and its use for the formation of radiation pressure is explained by the following circumstances:

- in the ultrasonic range, higher values of radiation power are achieved (up to 5 W / cm ² ), [9, 10];

- in the ultrasonic range, the overall dimensions of the emitter are significantly reduced at low (not more than 100 V) supply voltages of the radiating elements.

The features of ultrasonic emitters are the realization of the resonance phenomenon in mechanical vibrational elements, which allows one to significantly increase the amplitude of oscillations at the resonant frequency. In the region of the indicated ultrasound range, materials having a piezoelectric effect are used. Such plates are polarized in thickness Δ, and the maximum radiation efficiency is achieved when Δ is equal to the half-wavelength of the radiation λ _rad / 2 (at a frequency of 50 kHz λ _rad / 2 = 5.5 mm).

As materials with a piezoelectric effect, zirconate - lead titonate (TsTS-22, TsTS-23, TsTBS-2, TsTSS-1), lithium niobate (NBS-1), etc., which have high permissible operating temperatures (higher + 300 ° C). Ultrasound emitters with a radiation power of 5 W / cm ² have an efficiency of about 30%, which is almost an order of magnitude higher than the efficiency of emitters in the sound and infrasonic frequency ranges [11].

With the intensity of ultrasonic radiation I _{knots, the} generated sound pressure ∆P _knots can be calculated using the expression [12, 13]:

$$\Delta P_{\mathrm{at}s}=\sqrt{I_{\mathrm{at}s}\cdot Z_{\mathrm{but}\mathrm{to}}}(\mathrm{four})$$

and at I _knot = 5 W / cm ² Z _ak ≈418 kg / m ² · s (acoustic resistance of air) and ΔР _knot = 4.6 · 10 ³ Pa. The radiation pressure in this case is 4.6 ÷ 46 Pa.

The obtained value of radiation pressure should be attributed to the values that cause pain in a person in the sound range [12, 13]. This result is confirmed by the experimental data presented in [6], where it was recorded that at a sound intensity in air of ~ 1 W / cm ² (corresponding to a sound intensity level of ~ 160 dB), sound pressure is ~ 3 · 10 ³ Pa, and radiation pressure is ≈10 Pa.

In accordance with the proposal, the ultrasonic emitter operates in a pulsed mode with a frequency of 1 Hz or higher and creates a radiation pressure equivalent to the infrasonic pressure indoors.

In [2, 5], the resonance frequencies of the internal organs of a person are given, the performance of which may be affected by the radiation of the infrasound range:

0.05 ÷ 0.06; 0.1 ÷ 0.6 Hz circulatory system 0.5 ÷ 13.0 Hz vestibular apparatus 2.0 ÷ 3.0 Hz stomach 2.0 ÷ 4.0 Hz intestines 2.0 ÷ 5.0 Hz hands 6.0 Hz spine

The types of changes in the mental state of a person who finds themselves in the field of infra-low radiation frequencies are as follows:

 heart rate reduction  1 ÷ 2 Hz  fear, disturbance of rest 8 ÷ 13 Hz (coincides with the delta rhythms of the brain)  mental impairment 14 ÷ 30 Hz (coincides with the beta rhythms of the brain)  dizziness 12 Hz  stomach upset 2 ÷ 4 Hz  anxiety, fear 15 ÷ 18 Hz

The information provided does not contain data on exposure exposure confirmed by any experimental data. The authors did not find such data in the open press or on the Internet, however, the infrasound effect of radiation pressure on a person in the proposed embodiment is practically feasible.

The authors consider the most appropriate use of infra-low frequencies causing anxiety and fear (ranges 8.0 ÷ 13.0 Hz and 15.0 ÷ 18.0 Hz) or an upset gastrointestinal tract (2.0 ÷ 4.0 Hz).

Figure 1 presents the functional diagram of the device that implements the proposed method. In accordance with figure 1: security sensors 1 to turn on the ultrasonic generator 2 are located on the elements of the room (front door, window, ventilation hatch, etc.), through which unauthorized entry into the room is possible. Ultrasonic electric signals are fed to a modulator 4, which connects the ultrasonic generator 2 to the ultrasonic emitter 4. Key devices 5 provide the disconnection of the ultrasonic generator. The location of the elements 5 inside the enclosed space should be known only to the owner of the room, and they should be placed, if possible, in a place inaccessible to undesirable persons. Such a key can be made using an electromagnetic emitter controlled manually or a mechanical switch such as a button.

The work of the proposed method is illustrated in figure 2.

- when one of the security sensors 1 is “triggered” after a time t, the _back is fed, for example, the supply voltage U _p to the ultrasonic generator 2, which starts to operate in continuous mode, as shown in graphs A and B in figure 2.

The graph In figure 2 shows the operation of the modulator, which generates rectangular pulses of duration t _imp . In this case, the switching frequency of these pulses F _mod is in the range of infralow frequencies from 1 Hz and above.

Graph D shows the operation of the ultrasonic emitter during pulses generated by the modulator of duration t _mod .

Graphs D and E in figure 2 illustrate the moment of occurrence of the signal from the key 5 and the formation of radiation (infrasound) pressure.

With a change in F _modes with a constant duration of t _modes , a change in the duty cycle of the inclusion of the ultrasonic emitter occurs. Therefore, the authors proposed the requirement of maintaining the duty cycle of the inclusion of the ultrasonic emitter (the ratio of the modulation period 1 / F _mod to the radiation time t _mod ) for any values of F _mod in the form of the equality

$$\frac{\mathrm{one}}{F_{m\mathrm{about}d}\cdot t_{m\mathrm{about}d}}=2,0\pm 0,2$$

So, with a duty ratio of 2, the optimal values of the formation of the pulsed radiation power of the radiation infrasound pressure are achieved, which reduces the acting infrasonic radiation pressure of the radiation by half.

The deviation of 10% (2 ± 0.2) from the optimal value of the duty cycle of radiation, according to the authors, is permissible, since it leads to a change in the radiation pressure of sound within 10%. Deviation from the indicated spread leads to complication of the ultrasonic generator and radiator circuits, as well as to undesirable pressure changes.

As noted above, the radiation pressure of ultrasound radiation is formed due to the difference in acoustic impedances in the air during the formation of rarefaction and compression regions in the air in the direction of wave propagation. Also, such pressure will be formed during the propagation of ultrasound radiation in liquid and solid media.

It seems obvious that an increase in the number of formation of these regions, that is, an increase in the number of periods of oscillations in the interval of t _modes during operation of the ultrasonic emitter, can lead to the rapid formation and increase of radiation pressure. In particular, for the case of equality of duty cycle 2 and at F _kn = 40 kHz for F ' _mod = 1 Hz, the number of periods of oscillation with ultrasonic radiation is 2 · 10 ⁴ , and at F'' _mode = 18 Hz the number of periods is 10 ³ .

However, it is known [13] that sound absorption is observed not only by obstacles, but also by the air. These losses are due to viscosity, thermal conductivity and molecular absorption. Sound absorption in air is quite accurately described by an exponential function of the form

$$\epsilon ={\epsilon }_0\cdot \exp (-\mu \cdot l)(5)$$

where l = c _sv · t, µ is the attenuation coefficient equal to the reciprocal of the path l on which the initial density of sound energy ε ₀ decreases by a factor of e.

The value of µ depends on the density ρ _{0 of} air, its viscosity η, temperature T, humidity φ, frequency F and is expressed by the dependence

$$\mu =52,5\cdot \eta \cdot \frac{F_{\mathrm{at}s}^2}{c_{s\mathrm{at}}\cdot {\rho }_0}=A\cdot F_{\mathrm{at}s}^2(6)$$

From (6) it follows that, ceteris paribus, for different F _{knots, the} amount of sound energy loss will be the same when the condition

$$\frac{l_{\mathrm{one}}}{{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="00000019.png"\; state="\{\{state\}\}">l</figure-callout>}}_2}={\left(\frac{F_2}{F_{\mathrm{one}}}\right)}^2(7)$$

and, therefore, for the proposed method of changing the ultrasonic frequency above 30 kHz (for example, in the range up to 50 kHz), the ratio will be l ₁ / l ₂ ≈ 2.8. This means that the loss of radiation power at a frequency of 50 kHz in air will occur at a distance l ₂ , which is three (≈2.8) times less than the distance at which the same losses occur at a frequency of 30 kHz.

Approximately the same result follows from the graph given in [12], in which the loss in dry air at a frequency of 30 kHz is 105 ÷ 115 dB, and at a frequency of 50 kHz - 300 ÷ 320 dB.

Therefore, according to the authors, the frequency of the ultrasonic emitter should be set close to the upper boundary of the sound frequency in the range of 30 ÷ 50 kHz.

For small premises (for example, a car interior), the choice of F _{knots is} correctly evaluated only by the frequency dependences of the absorption coefficients of the walls of the room, neglecting radiation losses in the air.

According to the authors, the radiation pressure of the ultrasonic radiation that occurs during t _modes , at the end of this time, should decay to almost zero in a time equal to or less than 0.25 t _modes . The process of attenuation of ultrasound radiation, as is known, is determined by two factors:

- the presence of absorption of ultrasound radiation by the walls of the room, which can also be estimated by the reflection coefficient of the walls,

- viscous attenuation of the ultrasonic wave in air, which is insignificant for rooms of small size (volume) in the indicated range of F _knots .

In acoustics [12, 13], the time during which the sound energy in a closed room after turning off the sound source decreases to some predetermined level is called the reverberation time T _roar . For a given duty cycle of the ultrasonic emitter (condition (1)), the authors recommend a reverberation time that ensures the implementation of the proposed method, to establish from condition (2). Of course, the time T _roar depends on the volume of the room and the reflection coefficients α of its walls, assuming that the absorption coefficient of walls β with a known α is found from the obvious equality

$$\beta =\mathrm{one}-\alpha (8)$$

For example, consider two closed rooms in the form of a cube with sides α '= 1 m and α' '= - 4 m. The average wavelength in the first room can be [13] ≈3 m, and in the second ≈5.5 m , and the wave travel time of this distance will accordingly be

c и $$\Delta t_{\alpha \text{'}\text{'}}=\frac{5,5}{C_{зв}}\approx 16,2\cdot {10}^{-3}$$

с $$\Delta t_{\alpha \text{'}\text{'}}=\frac{3}{C_{s\mathrm{at}}}\approx 8,8\cdot {10}^{-3}$$

c and $$\Delta t_{\alpha \text{'}\text{'}\text{'}\text{'}}=\frac{5,5}{C_{s\mathrm{at}}}\approx 16,2\cdot {10}^{-3}$$

from

Since the time T _roar must satisfy condition (2), for various values of F _{modes the} number of reflections n _OT in the room is limited by the inequality

$$n_{\mathrm{about}tR}\le \frac{0,25}{F_{m\mathrm{about}d}\cdot \Delta t_{\alpha }}(9)$$

Table 1 shows the calculated values for various F _modes when using equality in (9).

Table 1 F _mod , Hz 2 5 8 12 eighteen 0.25 / F _mod , s 0.125 0.05 0,031 0,0208 0.01375 n _neg Δt _{α '} 14.2 5.7 3,5 2,4 1,6 Δt _{α ''} 7.8 3,1 1.9 1.3 0.9

From the data in table 1, we can draw the following conclusion:

- with an increase in the volume of the enclosed space, the number of reflections n _sp radiation from its walls decreases and, therefore, the use of a material with a large absorption coefficient β (or lower reflection coefficient α) of the walls is required,

- the most appropriate when implementing the proposed method to use the volume of the premises is not more than 60-70 m ³ at a modulation frequency F _mod ≤13 Hz.

Since the reference literature on acoustics often cites data of reflection coefficients α of sound waves from various obstacles, the expression for determining the required value of α can be represented as

$${\left(\alpha \right)}^{n_{\mathrm{about}tR}}=\Delta P_{\min },(10)$$

where ΔP _min - the minimum level of decline of the original unit of measurement (pressure, power) at the end of the radiation, which occurs after a time T _roar . This level is set. For example, for ΔP _min = 0.001, the required reflection coefficient is found from the expression

$$\alpha =\sqrt[n_{\mathrm{about}tR}]{0,001}$$

and at F _mod = 8 Hz and a room with n _OTR = 3, the reflection coefficient α = 0.1 (β = 0.9), and for rooms with n _OTR = 6, the reflection coefficient α = 0.316 (β = 0.684).

The authors proposed restriction on the response time t _ass <15 s due to the following circumstances:

- a possible delay before the entry of unwanted persons into the room for various reasons,

- a possible loss of a key for opening the lock device by the owner of the room, who knows the location of the key 5 (see figure 1) and the secret to disconnecting it.

The delay time t _{ass is} set by agreement with the owner of the premises, observing the requirement not to exceed 15 s.

Thus, a method of protecting a closed room with unauthorized entry into it is proposed, based on the effect of radiation pressure on these persons during pulsed radiation of ultrasonic vibrations with a frequency of their inclusion in the infrasonic frequency range from 1 Hz and above.

The choice of the frequency of infrasound is the prerogative of consumers, but with the obligatory observance of restrictive legislative measures for the use of these types of radiation.

The recommended range of ultrasonic radiation during the formation of radiation pressure allows us to successfully solve the technical problem - reducing the geometric dimensions of the infrasound emitters when the effective power of the ultrasound radiation is reached.

In this application, the direct effect of ultrasound radiation on a person was not considered, since at the indicated frequencies and radiating ultrasonic power, the authors did not find any danger to humans in the well-known literature.

References

1. Khorbenko I.G. Sound, ultrasound, infrasound. M .: 1986.

2. Khatuntsev Yu.A. Ecology and environmental safety. - M.: 2002.

3.http: //vaostory.m/blogs/o-chyom-malo-pishut/infrazvukovoe-oruzhie.html. Web, 02.24.2012.

4. http://gorod-magov.ucoz.org/forum/161-197-1. Web, December 4, 2008

5. GOST R 53188.1-2008, Sound level meters. Part 1. Technical requirements. - M .: Standartinform, 2009, 32 p.

6. Krasilnikov V.A. Krylov V.V. Introduction to physical acoustics. - M .: Nauka, 1984, 403 p.

7. Prokhorov AM. (Ed.) Physical Encyclopedia, - M.: Science, 1983.

8. Kolesnikov A.E. Ultrasound Measurement, Moscow: Nauka, 1970.

9. Rosenberg L.D. The use of ultrasound, - M .: AN USSR, 1958.

10. Reference, ed. Klyueva V.V. Non-Destructive Testing and Diagnostics, 2nd ed., Revised. and add. - M.: Mechanical Engineering, 2003 .-- 656 p.

11. Krasilnikov A.A. Sound and ultrasonic waves in air, water and solids, - M.: Fizmat literature, 1960.

12. Handbook "Acoustics", - M .: Radio and communications, 1989.

13. Aldoshina I.A., Vologdin E.I. Efimov A.P. et al. Electroacoustics and sound broadcasting, - M.: Radio and communications, 2007.

Claims (1)

A method of protecting a closed room in case of unauthorized entry of undesirable persons into it through the entrance door (s) equipped with a special locking device, characterized in that the entrance door, windows, and ventilation hatch are additionally provided with key elements which, when unauthorized entry through the aforementioned elements after a time t _ass ≤15 s include an ultrasonic (ultrasonic) oscillation generator that operates continuously at one fixed frequency above 30 kHz, and which is connected to the ultrasound through a modulator the teacher (s) of oscillations, the radiation of which (s) is directed inside the room, and the ultrasonic emitter is turned on by rectangular pulses and of duration t _modes with a modulation frequency F _mode in the range from 1 Hz and above, while the duty cycle of the ultrasonic emitter is set from equality
$$\frac{\mathrm{one}}{F_{m\mathrm{about}d}\cdot t_{m\mathrm{about}d}}=2,0\pm 0,2$$

,
reverberation time T _{roar of} ultrasonic radiation at the end of t _{mod is} established from the inequality
$$T_{Re\mathrm{at}}\le \frac{0,25}{F_{m\mathrm{about}d}}$$

,
and the reflection coefficient of ultrasonic radiation of the walls of a closed room is determined from the equality
$${(\alpha )}^{n_{\mathrm{about}tR}}=\Delta P_{\min }$$

,
Where $$n_{\mathrm{about}tR}=\frac{T_{Re\mathrm{at}}\cdot C_{s\mathrm{at}}}{l_{\mathrm{from}R}}$$

- the average number of reflections in the room, l _cf - the average wavelength between reflections, C _Sv - the speed of sound in air, ΔP _min - the minimum level of decline of the original unit of measurement (pressure, power) at the end of time T _roar .

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