The Optimum Thickness of Rockwool as Roof Thermal Insulation: An Experimental and Numerical Study

Now a days, the global warming has increased the temperature in the environment that forced the building occupant to get assisting from the air condition to reduce the heat tension inside the building, this could increase the electricity bill amount. The aim of this study is to measure the optimum thickness of Rockwool insulation to experimentally and numerically to reduce the heating load inside the buildings. Two devices have been used through this research, Infrared Thermometer to measure profile temperature of the walls along with VELOCICALC to measure the air temperature and air velocity. Three different layers of Rockwool insulation have been applied on the roof of wooden room. The data present the two layers thickness of Rockwool is the best selection to reduce the heating load inside the room, the differential between outside and inside is 0.9 °C, the Rockwool of one layer reduced only 0.5 °C and the maximum thickness with three layers reduced only 1 °C, which is not much effective compared to the two layers but even more costly. CFD analysis shows agreement with the experimental result. The results shows if the dimensions of a UCSI lecture room is to be considered, then applying Rockwool insulation with a thickness of 100 mm would cost around RM 1520 as a UCSI lecture room is of 8 m width and 9 m length. However, two layers of Rock wool insulation could save around 29.30% of ROI per annum.

Thickness-Dependent Photocatalysis of Ultra-Thin MoS2 Film for Visible-Light-Driven CO2 Reduction

The thickness of transition metal dichalcogenides (TMDs) plays a key role in enhancing their photocatalytic CO2 reduction activity. However, the optimum thickness of the layered TMDs that is required to achieve sufficient light absorption and excellent crystallinity has still not been definitively determined. In this work, ultra-thin molybdenum disulfide films (MoS2TF) with 25 nm thickness presented remarkable photocatalytic activity, and the product yield increased by about 2.3 times. The photocatalytic mechanism corresponding to the TMDs’ thickness was also proposed. This work demonstrates that the thickness optimization of TMDs provides a cogent direction for the design of high-performance photocatalysts.

Modifications of Phytoseiidae mite breeding methods to suppress spider mite

Populations of mites from the Tetranychidae family are characterized as high-resistant to acaricides, which, in turn, leads to an increase in the pesticide load on the agrocenoses ecosystem. Carnivorous arthropods from the Phytoseiidae family can be used as an alternative pest control. Our research aimed at improving the methods of breeding, storage and use of predatory mites against Tetrahychus urticae Koch. In 2015–2018, work was being undertaken to define the optimum thickness of the substrate layer (2.0, 4.0 and 6.0 cm) for breeding the food object – Acaris farus Oud. We also assessed the effect of the fodder substrate composition (wheat bran – control, wheat bran + soybean meal – experimental variant) on the population density of Amblyseius andersoni Chant. In 2016–2019, experiments on the storage of Neoseiulus barkeri Hughes, Neoseiulus cucumeris Oud. and Amblyseius swirskii Athias-Henriot at 4 °C (control – no storage) were carried out. In 2018–2019, to control Tetrahychus urticae Koch. in the soybean field, a mixture of N. cucumeris and A. andersoni was used according to the method of introduction into natural foci of prey. The optimum thickness of the substrate layer was found to be 4 cm. In this case, it was possible to obtain 6,983 mites in 1 cm3 for 7 days. Soybean meal addition increased the number of A. andersoni by 22.3 % compared to control (263 ind. vs 204 ind. per cm3). 30–45 days – an effective storage period for N. barkeri, 30 days – for N. cucumeris, no more than 10 days – for A. swirskii. On average, in 2018–2019, N. cucumeris and A. andersoni mixture reduced the number of T. urticae. The number of spider mites in the control variant was 14.6, in the experimental one – 5.3 ind./leaf. No predatory activity was observed on eggs. To prevent the development of spider mites, it is necessary to use N. cucumeris and A. andersoni at least twice with an interval of 5–7 days.

Radiation Protection of Personnel in Contact Radiation Therapy in Ophthalmology

Purpose: To ensure radiation safety of medical staff personal protective equipment (PPE). Material and methods: In order to not make assumptions of possible protective materials optical distortion, estimated the dependence of light transmission in the wavelength range 330–660 nm leaded glass brands of TF-1 and TF-5, as well as the intensity of glow glasses when exposed to light and X-rays. Results: We trace the degree of browning and the nature of the recovery of transparency of glass after irradiation. To determine the optimum thickness of lead glass for eyewear experimentally evaluated attenuation of X-rays with energy efficiency 30 and 80 keV. Lead equivalent values for lead glass, was determined so for Eeff ~ 20 keV at a multiplicity of weakening k = 10 lead glass brand TF-5 thickness 2.0 mm equivalent 0.8 mm Pb, etc. For the possible use of other additives in the window shows the curves of the attenuation of photon radiation radionuclide 241Am (20–60 keV) filters from 9Be, 26Al, 56Fe, 64Cu, 99Mo, 112Cd, 184W, 207Pb Conclusion: Possible introduction of new dose limits for the lens of the eye can be successful only in case of both existing and newly developed PPE. To reduce the impact of domestic lead glass radiation can be used for staff in the form of screens and glasses.

Optimum Thickness of Thermal Insulation with Both Economic and Ecological Costs of Heating and Cooling

The energy efficiency of the construction sector should be determined by the cleanliness of the environment and, thus, the health of society. The scientific aim of this article was to develop a methodology for determining the optimum thickness of thermal insulation, taking into account both economic and ecological aspects and considering both heating and cooling costs. The method takes into account the number of degree days of the heating period, as well as the number of degree days of the cooling period. Variants in terms of different types of thermal insulation, various types of construction materials for building walls, climatic zones and heat sources, were taken into consideration. In order to find the optimum thicknesses of thermal insulation, both in economic and ecological terms, a metacriterion was used. The optimum thicknesses of thermal insulation with the use of the metacriterion were obtained in the range of 0.11–0.55 m. It was observed that the values of the optimum heat transfer coefficients for economic and ecological reasons do not depend on the type of construction materials used for vertical walls. The type of applied heat source is of the greatest importance for the size of the economic and ecological benefits. The proposed mathematical model for determining the optimum thickness of thermal insulation with the use of a metacriterion is a kind of generalization of earlier models from the literature.