Papers by Keyword: Shielding

Abstract: The contributions balance of isolation and cooling effects relative to the liquids surface to slow down their evaporation and to achieve safe vapor concentrations is determined. The influence of liquids characteristic temperatures and their water solubility on this process is considered. It is proven that the long-term effect of such means is provided by systems based on closed-pore floating solid materials (for example, foam glass). It is proposed to increase the foam glass low isolation and cooling capacity either by coating it with an inorganic gel or by wetting it with water. Smaller evaporation retardation coefficients by gel were obtained for liquids with the higher water solubility. A 5–6 times greater cooling capacity of the wet foam glass than dry foam glass was obtained for both polar and non-polar liquids. A smaller cooling effect is observed for liquids with a higher vaporization heat and is similar for both the use of the dry and wet foam glass. It was found that for low-boiling non-polar liquids, the evaporation slowing down is more effectively achieved by using isolation effects, and for high-boiling polar and non-polar liquids - by using cooling effects. It is proved that the fire extinguishing effect by applying the foam glass layer on the flammable liquid surface occurs in a similar way for liquids with close equivalent cluster lengths and not flash temperatures.

Abstract: The designed is a cement-silicate coating based on liquid sodium glass and Portland cement, modified with a complex ultra-and nanodispersed additive that includes titanium dioxide, expanded perlite sand and a dispersion of multilayered carbon nanotubes. The advantage of the designed coating is the use of Portland cement as a silicizer instead of conventionally used zinc oxide. The presented cement-silicate coating is water resistant, steam and gas proof, has good adhesion to the base and an increased durability, providing 4-5 times longer service life than those of the existing analogs. The presence of multilayered carbon nanotubes in the coating leads to the absorption of technogenic electromagnetic emission, and ultradisperse titanium dioxide promotes self-cleaning of the coating surface due to the photocatalysis effect. Expanded pearlite sand makes the coating surface textured when applying it to the base. The cement-silicate coating is used for facades decorative finishing of buildings made of ceramic bricks, cement concrete and plastered surfaces.

Abstract: This work, gamma-ray shielding properties of the lutetium lithium borate glasses in the system Lu₂O₃ - Li₂O - B₂O₃ have been evaluated as a shielding material at 662 keV photon energy. While the experimental mass attenuation coefficients (μ_m) have been determined by using the narrow beam transmission method, the theoretical data were calculated using WinXCom program. The good agreements between experimental and theoretical values have been obtained. Both experimental and computational mass attenuation coefficients data were used to obtain the effective atomic number (Z_eff), and the effective electron density (N_el). Based on the obtained data, the Lu-based glasses have good shielding properties, the improved glasses could be used as gamma-rays shielding material.

Abstract: Generally, electric and magnetic interference will affect in high resistance measurements. This causes a large number of the standard deviation of measurement as well as the accuracy and result of measurement. The purpose of this research is to study the effectiveness of shielding and guarding on the measurement system. In experimental setup, the 1 GΩ resistance was supplied by voltage source of 100 V, 500 V and 1000 V in with and without shielding and guarding. The resistance value and standard deviation were measured and compared in each case of measurements. From the experimental results, when applying shielding and guarding, the noise can be reduced. As a result, the standard deviation was decreased more than 10 times.

Abstract: Using three types of yarns with metal filaments, textile samples with various arrangements of yarns were made and additionally coated with polyurethane and graphite layer. The aim of the study is to identify the metal filaments fabrics with the highest shielding effectiveness (SE) and influence of graphite layer on it, using a waveguide method and network analyzer with radiated frequency from 2.6 – 3.6 GHz. Layer of graphite improves the SE properties, although, some uncoated samples have higher SE for definite frequencies.

Abstract: Anechoic chambers are widely used in performing EMC measurements according to the established EMC standards. As in space area, EMC measurement is critically important to ascertain all of electrical and electronic components in the satellite body will function correctly without fail during launching and operation mode. Recognizing the needs and importance of performing the EMC measurements, the shielding performance of the chamber should be prioritized to ensure the interference of electromagnetic wave from outside going to inside the constructed chamber does not exist. As to maintain the shielding element, periodic checking and inspection should be well planned by conducting a specific test. This paper outlines a series of procedures that are developed while running the test. The test will characterize the shielding performance at four (4) frequency ranges using different types of antenna set. Typical test results are gathered and presented at the measured frequencies. Based on the results, it is concluded that the shielding performance of anechoic chamber is standing in good condition at three (3) ranges of frequencies except for frequency of 10 kHz to 200MHz. Several steps are recommended to remove or eliminate the random noise.

Abstract: W@SiO₂ shielding composite microspheres were prepared by Sol-gel method for the first time. The component and morphology were investigated by Fourier transform infrared (FT-IR) spectra, Transmission electron microscopy (TEM) and Energy dispersive X-ray spectroscopy (EDX). The results reveal that polyvinylpyrrolidone (PVP) was introduced to the surface of tungsten nanoparticle successfully, and tungsten nanoparticle had been coated with silica. The appropriate hydrolysis reaction time is 3h, core-shell structure W@SiO₂ shielding composite microsphere can be synthesized and free silica decrease sharply. Core element and shell element of W@SiO₂ shielding composite microspheres were proved to be tungsten and silica respectively.

Abstract: Now more power electromagnetic equipments are used. The radiation of them affects the human health and the environment. According to the mechanism of electromagnetic radiation and the influencing factor of electromagnetic pollution, the paper has researched electromagnetic radiation shielding measures. It was analyzed that the feasibility and application methods and results of steel fiber reinforced concrete (SFRC) building constructs. The application prospect and value of SFRC were brought out.

Abstract: Glasses composition of xSrO:(70–x)B₂O₃:30SiO₂ when 25≤x≤50 mol% were prepared using the melt quenching technique and investigated the other properties of glasses. The density of the glasses was measured using Archimedes’ principle; the molar volume of the glasses has been derived from density measurements data. The hardness of glasses sample was measured by using the Vickers hardness. Mass attenuation coefficients have been determined experimentally for the glass system at photon energy 662 keV, the results compared with theoretical calculations from WinXCom computer software. The reported data should be useful for decision chosen of these glasses in radiation shielding.

Abstract: Basic on the problem that the electromagnetic environment in vehicles which formed at the moment of ignition will cause interference to the stability and reliability of vehicle safety system, the paper takes vehicle fire protection system as the research object, and analyzes the interference mechanism and harmfulness through the simulation experiments. Finally uses the related software design and some prevention measures for electromagnetic interference such as shielding, grounding to protect the system, then through experiment to verify that it’s scientific and reasonable.