Creation of means of active protection of objects located near water areas. physiological aspect..
UDINTSEV Dmitry Nikolaevich, Candidate of Technical Sciences
CREATION OF MEANS OF ACTIVE PROTECTION OF OBJECTS LOCATED NEAR WATER AREA. PHYSIOLOGICAL ASPECT
A brief analysis and generalization of the results of previously conducted experimental studies of the electrophysiological effect of the electric field of current (EFC) in water on biological objects is presented. A method for assessing the influence of EFC on the performance of actions by an intruder is proposed.
Due to the increased activity of global terrorism in recent years, more and more attention has been paid to the protection, security and defense of various objects. Many of them are located near sea and river waters. For example, road and railway bridges, hydraulic structures, nuclear and hydroelectric power plants, chemical plants, etc.
In the near future, significant successes of domestic and foreign developers and manufacturers of technical security equipment in the development of perimeter security systems will significantly complicate, if not make it completely impossible for intruders to penetrate by land. In a separate series of situations, this may of course lead to the intruder abandoning his intentions, the most dangerous and “persistent” ones will be pushed to search for alternative methods (paths) of penetration. Of the remaining two options: by water and by air, the first is the most accessible, covert, and preferable for unauthorized penetration.
The analysis showed the extreme scarcity of the arsenal of technical means of detection in water and the almost complete absence of means of active influence on an intruder in water. One of the methods of active influence is to ensure such parameters of the EPT in a certain section of the aquatic environment that make it difficult for an intruder to overcome the water line or make it completely impossible. The creation and use of such means is complicated by the lack of a regulatory framework governing the use of EPT in water to influence an intruder. This framework should be based on scientifically substantiated and duly approved electrophysiological requirements for the parameters of the electric field of the current created by active protection means in water.
Despite the large volume of scientific literature devoted to the biological effect of electric current on animals or humans when they are on land or in the air, there have been very few targeted in-depth studies on the effect of the electric field of the current on biological objects in the aquatic environment. In addition, there are no systematizing works that allow the accumulated volume of knowledge to be fully used for the purpose of creating means of active protection of water areas (MAPA).
The effect of EPT on fish, which are considered the most sensitive biological objects to it, has been most fully studied [17]. This has found wide practical use in the form of technical means for electric fishing [1, 2, 3, 4].
The choice of the value of the impact parameters is determined by the type, size of the fish, fishing conditions (temperature, water salinity). For example, when fishing for fast-swimming predatory fish, lower voltages are used between the electrodes, shorter pulse duration, but their higher frequency than when fishing for sedentary fish [5].
The ratio of the electrical conductivity of water and the biological object itself has a significant effect on the damage. It is noted [6] that in cases where the electrical conductivity of water is less than the electrical conductivity of the fish, the EPT near it is distributed so that the potential difference between the most distant points of the fish's body in the direction of the orientation of the EPT force lines is less than the potential difference in the undisturbed field at a distance corresponding to the length of the fish. The current density in the fish's body is higher than in the environment. If the electrical conductivity of water is greater than the electrical conductivity of the fish, the opposite pattern is observed [7].
The convulsive effect of low-frequency EPT was assessed in experiments on dogs [8]. In this case, by analogy with land-based electrical protective equipment (EP), the current flowing through the human body was determined by calculation. The authors of this work came to the conclusion that even with a current of 15-20 mA, which does not pose an immediate danger to life under normal conditions (on land), when the object is on the surface of the water, the action of the EPT can lead to the death of the animal due to limb convulsions. A similar danger of drowning exists for humans. In this case, after stunning with electric current, the restoration of spontaneous breathing is observed earlier than the first attempts to surface. An analysis of the extremely few sources of available scientific literature allows only an approximate determination of the values of the EPT parameters in the aquatic environment, which can have a damaging effect on humans. In this regard, the data of some authors on the safe values of the electric field strength of the current and the current passing through a person in water are of interest. Thus, in the work [9], devoted to electrical safety when fishing using low-frequency pulsed currents, it is indicated that at an EPT intensity of 9.9 V/m, a sensation of jolts in the groin area appears. In this case, the frontal plane of the human body was oriented along the field lines of force, and sea water had a specific conductivity of 1 — 2 S/m. At the same time, as other authors note [10, 11], a swimmer in sea water may experience a loss of muscle control in the legs, leading to the inability to swim, already at an EPT intensity of 6.6 V/m. The observations presented are consistent with the data presented in [12 — 15].
All these studies did not answer the questions:
What effect does an EPT, which by its characteristics is insufficient to create a damaging (lethal) effect, have on the violator's performance of his actions? Considering that in most situations when guarding objects, the defeat of a swimmer is extremely undesirable, then without a clear answer to this question, the task of creating an APS cannot be solved.
How, according to the available data about the parameters of the EPT that are safe for human life, without conducting additional studies associated with increased danger, to determine the characteristics of the field corresponding to the lethal effect, under these conditions? Knowledge of the dangerous parameters of the EPT is necessary to justify the requirements for the safe operation of the SAZA.
Below are brief results of an attempt to systematize the results of previously conducted experimental studieselectrophysiological impact of EPT on biological objects with the aim of using them to solve the problem of creating means of active protection of water areas.
Of the known types of impact of electric current on a person: thermal, chemical, biological and mechanical [16], the decisive one in our case is the last one. The main cause of death of people in water is forced convulsive contraction of skeletal muscles. It was also noted that EPT in water, in addition to the physiological effect on the muscular system, creates a suppressive effect in the head area. A sensation similar to strong noise exposure is observed.
The physiological effect of EPT on the human body in water has the following features that distinguish it from the effects of electric current on land:
1. To damage a person in water, it is not necessary to achieve cardiac fibrillation and damage to the central nervous system. It is enough to provide a convulsive effect in one of the motor belts (upper and lower).
2. The specified degree of impact (defeat or repulsion) is achieved not immediately, as when touching the current-carrying parts of land EZs, but as the person moves toward the source of the EPT (in our case, to the linear part of the SAZA), it increases gradually.
3. The optimum frequency of the EPT effect in water is shifted by approximately an order of magnitude relative to the optimum effect of electric current on land and is within 200 – 800 Hz (Fig. 1) depending on the form of voltage supplied to the linear part (harmonic or pulsed), the duration of pulses with pulsed power supply, the parameters of the external environment in which the person is located and his physiological state.
There are the following thresholds of perception of EPT by a bioobject under its influence:
1. Sensation threshold– such a value of the EPT characteristic at which the biological object begins to feel the effect of the EPT on it;
2. The threshold of insurmountability (intolerance) of painful sensations (pain) – such a value of the EPT characteristic at which volitional overcoming of pain becomes practically impossible;
3. Damage to the biological object – complete loss of the ability to move in water and, as a consequence, drowning.
The factors influencing the degree of impact of the EPT in water on biological objects include:
— maximum potential difference on the part of the human body located in water;
— frequency and modulation-time characteristics of the EPT;
— electrical, magnetic and other properties of irradiated objects and the environment;
— structure of the EPT (in case of non-uniform);
— conditions of exposure, including the orientation of the intruder's body when moving in water.
Fig. 1. Dependence of the maximum potential difference on the body of an unprotected person on the frequency for the onset of threshold modes when exposed to sinusoidal EPT. (Confidence probability for the sensation threshold is 0.8, for the damage mode — 0.5; the confidence interval is shown in the figure)
It has been established that the greatest depth of regulation of the degree of impact can be achieved by changing the maximum potential difference on the part of the human body that is in the water. Changes in other factors either lead to a less significant effect or are technically difficult.
The purpose of creating means of active protection of water areas is to ensure such physiological conditions in a certain section of the aquatic environment that make it difficult for an intruder to overcome the water line or make it completely impossible. In this case, the following options for the actions of a biological object are possible:
1. Despite unpleasant physiological sensations, the intruder overcomes the water line, but at the same time the speed of its advancement involuntarily decreases;
2. The intruder, for physiological or psychological reasons, refuses to overcome the water line;
3. The intruder is motionless due to damage to his EPT.
The other possible options for the intruder's actions do not meet the purpose of creating the APS.
The criterion of the EPT impact on biological objects is the change in the behavioral reactions of experimental animals. The objective characteristic of the physiological and mental impact of the SAZA field on the intruder is the time it takes him to cross the water line or the time it takes to perform another operation. In this case, the operation is some designated action in water, for example, planting a mine. In options 2 and 3, this time tends to an infinitely large value.
Although such a characteristic as the operation execution time determines the degree of impact on the intruder, it is not convenient to use, since it depends on the type of a specific operation (planting mines, transporting an explosive charge, etc.). Therefore, as the main value characterizing the degree of impact of the EPT on a biological object, it is advisable to use a more universal value called the coefficient of change in the operation execution time KI, and described by the expression:
KI = 
, (1)
where 
is the time it takes to perform an operation without the impact of EPT on the intruder; 
is the time it takes to perform the same operation under the same conditions, but with the impact of EPT on the intruder.
The coefficient of change in the operation execution time and the maximum potential difference on the intruder's body are related by the following empirical dependencies:
КИ = 1; 
(2)
КИ = 
; 
(3)
where 
is the effective value of the maximum potential difference along the longitudinal axis of the body part in the water; 
is the effective value of the maximum potential difference along the longitudinal axis of the body part in the water corresponding to the threshold of sensations (Fig. 1);
(4)
where DjПmax is the effective value of the maximum potential difference along the longitudinal axis of the body part in the water corresponding to the damage mode (Fig. 1).
(5)
The values of the coefficient of change in the operation execution time, sufficient for the threshold of sensations to be reached, -1; the threshold of pain intolerance -1.9 – 2.1; to ensure the failure of the offender to perform his task, more than 4.
As an example, Fig. 2 shows the results of calculating the dependence of the coefficient of change in the operation execution time on the maximum potential difference on the part of the human body located in water, with a specific conductivity 
= 0.01 S/m and a uniform EPT frequency f = 100 Hz.
In conclusion, it should be noted that equations (2 – 5) allow:
— for known values of maximum potential differences corresponding to the threshold of sensations and the mode of damage for a given EPT, for the current value of the maximum potential difference to determine the corresponding value of the coefficient of change in the time of execution of the operation;
— given the known values of the maximum potential difference corresponding to the threshold of sensations, the current maximum potential difference and the corresponding value of the coefficient of change in the time of execution of the operation, determine the values of the maximum potential difference corresponding to the mode of damage.
Fig. 2. Results of calculating the dependence of the coefficient of change in the operation execution time on the maximum potential difference on the part of the human body located in water with a specific conductivity of 
= 0.01 S/m and a uniform EPT frequency of f = 100 Hz
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