Aircraft performance and noise database together with operational weights (depending on flight distances) and operational procedures (including low noise procedures) significantly influence results of noise exposure contour maps assessment in conditions of real atmosphere. Current recommendations of the Standard SAE-AIR1845A allow the definition of flight profiles via solutions of balanced motion equations. However, differences are still supervised between the measured sound level data and calculated ones, especially in assessing the single flight noise events. Some of them are well explained by differences between balanced flight parameters (thrust and velocity first of all) and monitored ones by the traffic control system. Statistical data were gathered to make more general view on these differences and some proposal to use them in calculations has been proven. Besides, the real meteorological parameters provide inhomogeneous atmosphere conditions always, which are quite different from the main assumptions of the SAE-AIR1845A, stipulating inaccuracies of sound level calculations.

This paper reports the principles of design and the examined protective properties of liquid materials for shielding the electric, magnetic, and electromagnetic fields over a wide frequency range. The materials were made on the basis of iron ore concentrate and a pigment additive, with water-dispersed and geopolymer paints used as a matrix. The tests of protective properties for the electrical and magnetic components of the electromagnetic field of industrial frequency showed that the electric field shielding coefficients at a concentration of the screening substance of 15−60 % (by weight) equaled 1.1−8.6; magnetic field – 1.2−5.3. The shielding coefficients of the material based on a water-dispersed paint are lower than those of a geopolymer one, which can be explained by the oxidation of an iron-containing component and a decrease in electrical conductivity. The shielding coefficients of the electromagnetic field with a frequency of 2.45 GHz are 1.2−7.9. The highest coefficients are inherent in the material with filler made of iron ore concentrate and titanium-containing pigment powder in a ratio of 1:1. To design materials with the required (predictable) protective properties, the relative magnetic, dielectric permeability of materials was calculated. It is shown that the obtained data are acceptably the same as the results from direct measurements of magnetic and dielectric permeability and could be used to calculate the wave resistance of the material and the predicted reflection coefficient of electromagnetic waves. Thus, there is reason to assert the need to build a database on the frequency dependence of effective magnetic and dielectric permeability in order to automate the design processes of composite materials with predefined protective properties.

Development and investigation of protective properties of the electromagnetic and soundproofing screen

The study of the chemical composition and dispersion of iron ore dust, which forms during the enrichment of iron ore, proved its suitability to be used as a screening filler in the production of metal-polymer electromagnetic screens of large areas. We developed the technology of production of protective screening material in the form of a foam-latex with different content of iron-ore dust of different dispersion. We determined the dependence of the coefficient of screening of material and contribution of the reflection coefficient of ultrahigh frequency electromagnetic waves to it on the weight content of iron ore dust. The study showed that an increase in dispersion of metal and metal-containing particles by 10‒20 times increases the overall screening coefficient by 6‒8 times. At the same time, the reflection coefficient decreases from 0.25 to 0.10. We established that the guaranteed screening coefficient of the magnetic field of the industrial frequency is 1.8‒2.2 even for screening particles of 50‒100 µm sizes. We determined that a sharp increase in protective properties of materials occurs at the content of iron-ore dust of 11‒12 % in the polymer matrix. We investigated electrophysical properties (specific conductivity and dielectric permeability) of developed materials with different contents of metal and metal-containing substance. The obtained data are sufficient for calculational forecasting of protective properties of the electromagnetic screen based on the amplitude-frequency characteristics of the electromagnetic field, which needs to be screened.

This paper reports a substantiated method and a designed device for controlling the concentrations of air ions in premises in accordance with the European standards SBM 2015. The use of an ultrasonic humidifier with a capacity of 25 W for two hours increases the concentration of negative ions around the device from 240 to 560 cm-3, positive ones ‒ from 260 to 410 cm-3. The intensity of the electrostatic field of a polymeric coating decreases from 5.1 to 0.2 kV/m. The disadvantage of the humidifier is a small radius of influence (1.0–1.5 m) and the inability to control the polarity of ions. It has been experimentally established that air cooling systems (split systems) deionize the air of the premises. Degrees of deionization and dominating polarity are unpredictable and different for devices of different manufacturers and brands. To control the ion composition of the air simultaneously with the maintenance of normative relative humidity and stresses of static fields, the structure was proposed and the effectiveness of a bipolar ultrasonic air ionizer with adjusted performance and dominating polarity has been tested. The maximum productivity of the ionizer is 4,000–5,000 cm-3. The radius of exposure is 5 m (reducing the concentration of ions with a distance to 500 cm-3). To pass the ionized air through an air capacitor, the number and predominant polarity of air ions are regulated by the polarity and voltage on the covers of the capacitor. It was established that in order to service a room with an area of 50 m2, an ultrasonic emitter with a capacity of 25 W would suffice. The adjustability of the device performance makes it possible to reduce or increase the service area. The ability to purify air from suspended particles is shown. During the two hours of operation of the ionizer, the dust content decreased from 4.3–4.4 mg/m3 to 1.4–1.6 mg/m3.

We developed and examined protective properties of the metal polymeric electromagnetic screens. We used metal-containing particles of nano dimensions as a filler in the polymeric matrix. It was established that this provides shielding coefficient of 10 dB at the content of a metal substance of 11–12 %. In this case, reflection coefficients are 0.27–0.30. This is not attainable for the materials based on macro particles. It was found that increasing the dispersion of particles by 2–4 times reduces reflection coefficient by 0.15–0.20. We studied dependence of the electrical-physical properties of material on the content of a metal substance. This allowed us to calculate shielding coefficients and the contribution of protection to them due to the reflection of electromagnetic waves. Micro structural research revealed the uniformity of distribution of metal particles in the body of a polymer matrix. This has provided a possibility to calculate at their low concentrations the required coefficients using the relations for regular metal structures. We have demonstrated experimentally the possibility of fabricating electromagnetic screens of the gradient type in a single layer matrix.