Papers by Keyword: Infrared

Abstract: Due to the importance of environmentally friendly solvents, deep eutectic solvents (DES) have gained the attention of many. They have physical properties almost similar to ionic liquids, but DES is less toxic. In this study, several DESs have been produced using urea as a hydrogen bond donor (HBD). These DESs include choline chloride - urea, betaine - urea and magnesium chloride hexahydrate - urea. Infrared analysis results indicate the presence of hydrogen bonding between the hydrogen bond acceptor (HBA) and HBD, confirming the formation of DES. The absorption of these hydrogen bonds occurs in the range of 3600 - 2800 cm^-1, causing the absorption bands to broaden. The DESs produced can be used in various extraction and separation processes.

Abstract: Reflective heating polyester fiber is the fiber prepared by adding nanoparticle with reflecting infrared radiation into the polyester. The human body loses 60% of the total heat by heat radiation, but reflective heating fiber can reflect the body's infrared radiation back to the human body to minimize the loss of heat. In this paper, the purchased GTO powder is modified by silane coupling agent KH560, which is added into PET as a reflective heating powder, and PET fiber containing different content of GTO(0.3wt%,0.6wt%,0.9wt%) is prepared through adding masterbatch method. The particle size test shows that the average size of GTO powder modified by KH560 is about 180nm and the distribution is narrow, which meets the basic requirements of spinning. Through the SEM analysis of PET fibers cross-section, it is found that the GTO powder modified by KH560 were dispersed well in the PET substrate. The results of DSC and mechanical tests show that the fiber with 0.6wt% content of GTO powder have the improved elongation and the crystallinity degree. For the infrared thermal imaging and UV-VIS-NIR tests of the fabric, with the increase of the proportion of powder the infrared emissivity and reflectivity of the fabric increased, the warmth retention is also improved.

Abstract: In order to get the low transmission rate in both mid infrared atmospheric window and far infrared atmospheric window, an infrared frequency selective surface composed of two layers based on hexagonal ring structure was designed. Simulation analysis using CST electromagnetic software shown that the frequency selective surface had two stopbands in both 3μm~5μm and 8μm~15μm regions, of which the average transmittance is lower than 2.5%. Therefore, this frequency selective surface realized two stopbands in infrared wavebands; This paper analyzed the filtering mechanism of the frequency selective surface based on the effective medium theory. In the end, this paper researched the effect of electromagnetic wave polarization mode, incident angle and dielectric layer thickness on the transmission properties of the frequency selective surface. The results revealed that the transmission of frequency selective surface is insensitive to polarization mode and incident angle, while the dielectric layer thickness is an important factor to the transmittance of frequency selective surface.

Abstract: The central heating units of buildings are typically replaced every 20 to 30 years. There exists a variety of solutions for fuel-and gas-based units, but it would be advantageous to be able to use renewable energies. This would become possible by the combination of planar carbon-fiber-based infrared (IR) radiant heating foils with a heat pump providing hot water. The main goal of our proposed overall control strategy is to increase the energy efficiency while maintaining the thermal comfort for the residents. We examined the electromagnetic compatibility of the heating foils and simulated the relative contributions of the amount of energy provided by the heat pump and by the heating foils to obtain a maximum coefficient of performance for the combined heating system.

Abstract: A novel infrared photodiode based on a graphene/n-type silicon heterojunction is explored. The heterojunction photodiode of interest has a large Schottky barrier that results in a low dark current. Graphene serves as the absorbing medium at a wavelength for which silicon is transparent. Under infrared illumination, photo-excited electrons in the graphene gain energy and thus have a greater probability to overcome the barrier and contribute to the photocurrent. We have demonstrated photodiode operation of a graphene/n-Si heterojunction at 1.3 and 1.55 μm wavelength, with 14% internal quantum efficiency and 1.5 pW/Hz^1/2 noise-equivalent power, for potential use in silicon photonics.

Abstract: The exact determination of emissivity and the following determination of the surface temperature of glossy materials can be carried out e. g. after applying a material with a known value of emissivity on the surface (e. g. self-adhesive foil or spray tint). The contribution deals with other possibility of determination of surface temperature and the influence of emissivity of glossy materials using a metal shield that reduces the negative influence of the reflected radiation during the termographical measurement.

Abstract: It is possible to measure the surface temperature of a peripheral wall in a certain point with an advantage when using a technical device for elimination of reflected radiation. Other advantages of the diagnostics of the peripheral wall using the infrared termographic system after removing the mentioned technical device from the wall is, that if we determine (using the technical device) the surface temperature in a determined point, then we are, after inserting it into the termographic systém, able to determine retroactively the real value of the apparent reflected temperature, and this is even done with higher accuracy. Then we use the value for a termographic measuring of all the surface of the peripheral wall, keeping the same angle of scanning.

Abstract: The practical determination of the surface temperature and emissivity of glossy materials using the infrared thermography is carried nowadays in the way that the surface is covered with a material which has a known value of emissivity. The mentioned values are, however, possible to be determined even without the materials which havae a known value of emissivity: using the infrared radiation, which is reflected by the glossy surface and is detected by the termographical device afterwards. The contribution deals with the possibility of determination of surface temperature and emissivity of glossy materials by the mentioned method.

Abstract: The value of the surface temperature and emissivity of glossy materials can be determined by the method of four points. However, in practical measurements on the peripheral walls of buildings there may occur situations where four points are not available. In such case it is possible to use alternate sources of heat.

Abstract: Improving properties of materials is an integral part of almost of all remedial interventions; one of the most challenging remediation is the remediation of damp masonry. With the development of advanced technologies in the field of remedial chemicals there is one of the increasingly used methods – the method of high-pressure chemical grouting. Its use, however, raises the question how to control the quality of the design. This article deals with the possibility of mathematical modeling of grouting design of damp masonry and using the indirect method based on infrared radiation for subsequent checks.