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Experimental Assessment of the Effects of building materials on Wi-Fi Signal 2.4 GHz and 5 GHz

Journal of Computer and Communications 2024年第5期12卷 1-10页

作者： Sylhane Bytyqi Besfort Jashari Department of Telecommunication Faculty of Electrical and Computer Engineering University of Pristina Pristina Kosovo

We are all witnesses to the widespread use of wireless LANs (WLAN) and their easy implementation in indoor environments. Wi-Fi is the most popular technology for the WLAN. However, interference caused by building materials is a common, yet often overlooked, contributor to poor Wi-Fi performance. This interference occurs due to the nature of radio wave propagation and the characteristics of the wireless communication system. Therefore, during the implementation of these networks, one must consider the quasi-static nature of the Wi-Fi signal and its dependence on the influence of various building materials on the propagation of these waves. This paper presents the effects of building materials and structures on indoor environments for Wi-Fi 2.4 GHz and 5 GHz. To establish the interdependencies between factors influencing electric field levels, measurements were conducted in an experimental Wi-Fi network at different distances from the access point (AP). The results obtained show that the electric field strength of the Wi-Fi signal decreases depending on the distance, the building materials, and the transmitted frequency. Concrete material had the most significant impact on the strength of the electric field in Wi-Fi, while glass had a relatively minor effect on reducing it. Wi-Fi operates within the radio frequency spectrum, typically utilizing frequencies in the 2.4 GHz and 5 GHz bands. Additionally, measurements revealed that Wi-Fi signal penetration is more pronounced at lower frequencies (2.4 GHz) as opposed to the Wi-Fi signal 5 GHz. The findings can be used to address the impact of building materials and structures on indoor radio wave propagation, ultimately ensuring seamless Wi-Fi signal coverage within buildings.

关键词： WLAN Electric Field AP building materials Frequency Wi-Fi

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Green building materials lit up by electromagnetic absorption function:A review

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Journal of materials Science & Technology 2022年第17期112卷 329-344页

作者： Ting-Ting Liu Mao-Qing Cao Yong-Sheng Fang Yu-Hang Zhu Mao-Sheng Cao School of materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Heilongjiang Institute of Construction Technology Harbin 150025China

Healthy and livable living environments,as well as anti-electromagnetic(EM)radiation buildings,are the long-term goals of human *** introduction of advanced EM wave absorbing materials into buildings is one of the most feasible ways to address the increasing EM pollution in building ***-efficiency,broadband,low-cost and good building performance EM wave absorbing materials,as an important support in the field of sustainable building,has gradually become the hotspot ***,we review the research progress of building materials with EM wave absorption functions,and comb their classification,including cement,concrete,ceramics,and prefabs,especially highlighting the advanced coating *** objectively outline and evaluate the latest technology of building materials with EM wave absorption performance,and discuss the main problems and bottlenecks,highlighting potential research opportunities.

关键词： Anti-electromagnetic radiation building Electromagnetic wave absorption building materials Green building

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Fabrication of fire-retardant building materials via a hyper-crosslinking chemical conversion process from waste polystyrenes

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Energy and Built Environment 2022年第2期3卷 226-232页

作者： Changhui Liu Yuanhui Xie Ding Gao Xiancong Shi Zhonghao Rao School of Electrical and Power Engineering China University of Mining and TechnologyXuzhou 221116China

Polystyrene(PS)is rich in plastic materials,but it produces a large amount of waste every year,causing a huge burden on the *** PS plastic is the source of a common"white pollution"in daily life,it still has a high utilization *** the same time,the flammability of PS material determines that it cannot be applicated in places where fire accidents occur *** a result,its application has been greatly *** order to realize the efficient utilization of waste PS and broaden its scope of application,PS was modified by hyper-crosslinking in order to improve its fire-retardant *** this method,the PS solution with high purity was obtained by dissolving waste PS foam with 1,2-dichloroethane(DCE),and then the hyper-crosslinked polymer with high specific surface area was prepared by adding cross-linking agent formaldehyde dimethyl acetal(FDA)and a Lewis-acid catalyst ferric chloride(FeCl_(3)).Further studies showed that the effects of the amount of cross-linking agent FDA,catalyst FeCl_(3) and PS on the reaction products were *** addition,compared the as-prepared fire-retardant materials with PS foam from the aspects of flame retardancy and thermal insulation,it can be concluded that the fire-retardant performance of the materials prepared by this method has been significantly *** it is proved that this method is feasible towards the preparation of a large number of fire-retardant composite materials by using a scale-up experiment.

关键词： Waste polystyrene building materials Fire-retardant Hyper-crosslinking High-value added utilization

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Modeling chemical releases from building materials: The search for extended validity domain and parsimony

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building Simulation 2021年第4期14卷 1277-1293页

作者： Lei Huang Alice Micolier Henri P.Gavin Olivier Jolliet Department of Environmental Health Sciences School of Public HealthUniversity of MichiganAnn ArborMIUSA I2M CNRSUMR 5295351 Cours de la LibérationUniversity of Bordeaux33400TalenceFrance Department of Civil and Environmental Engineering Duke UniversityDurhanNCUSA

This study aims to systematically evaluate and extend the validity domains of multiple mechanistic models of chemical emissions from building materials. We compare the validity domain of the analytical solution with four numerical solutions for a single layer material with one convective surface and a wide range of chemical properties, material thicknesses, and simulation time. We also develop a parsimonious simplified model, ensuring the widest possible validity domain with minimum simulation time. For diffusion coefficients lower than 10−15 m^(2)/s, accuracy of the analytical solution requires at least 5000 positive roots. The numerical method using uneven discretization and finite difference approximation for the boundary conditions is the best numerical solution. The parsimonious combined D- and K-limited model achieves similar accuracy as the best numerical solution except slight overestimates at the interface between the D- and K-limited zones, while having simpler computations and much shorter simulation time. These models show good agreement against experimental data. This study demonstrates that the complex analytical solution can be well approximated by a simpler model with a wide validity domain, enabling the high-throughput screenings of a large number of chemical-product combinations.

关键词： emission models building materials organic chemicals analytical solution numerical and simplified solutions high-throughput assessment

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Industrial TiO2 based nacreous pigments as functional building materials:Photocatalytic removal of NO

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Chinese Journal of Chemical Engineering 2020年第10期28卷 2587-2591页

作者： Jue Li Li Wang Chunqiu Han Fengyun Su Yumin Leng Liqun Ye College of materials and Chemical Engineering Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion MaterialsChina Three Gorges UniversityYichang 443002China College of Physics and Electronic Engineering Nanyang Normal UniversityNanyang 473061China Engineering Technology Research Center of Henan Province for Solar Catalysis College of Chemistry and Pharmaceutical EngineeringNanyang Normal UniversityNanyang 473061China

In this paper,the photocatalytic activity of industrial titanium dioxide(TiO2)based nacreous pigments was researched as functional building materials for photocatalytic NO *** industrial TiO2 based nacreous pigments were selected to estimate the photocatalytic activity for NO *** study is a good proof that pearlescent pigments can eliminate NO,and its performance is positively correlated with its titanium dioxide *** this research will widen the application of nacreous pigments in functional building materials,and provide a new way to eliminate in door nitric oxide pollution.

关键词： Nacreous pigments Titanium dioxide Photocatalysis Nitric oxide Environment building materials

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Training Strategies of Practical Ability of building materials Professionals in Higher Vocational Colleges Under the Guidance of“Three Education Reform”Concept

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Journal of Contemporary Educational Research 2022年第8期6卷 9-15页

作者： Jing Sun Chongqing Energy College Chongqing 402260China

The main purpose of the implementation of the three-education reform concept is to improve the teaching quality and talent training level of higher vocational *** the reform,one can promote the optimization of teaching methods,provide more space for student’s self-development,and improve the quality of talent *** materials in higher vocational colleges are a high requirement for practical ability,which emphasizes the cultivation of students’practical *** the three-education reform concept,the traditional teaching mode should be replaced to provide more practical opportunities for students,in return give more attention to the development of students’practical *** paper mainly explores the current situation and training strategies in building material professionals in higher vocational colleges under the reform of the three education systems for a reference.

关键词： Vocational colleges building materials Practical ability of talents Cultivation strategy

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Monte Carlo simulation of indoor external exposure due to gamma-emitting radionuclides in building materials

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Chinese Physics C 2014年第10期38卷 126-130页

作者：邓君曹磊苏旭 Key Laboratory of Radiological Protection and Nuclear Emergency Chinese Center for Disease Control and PreventionNational Institute for Radiological ProtectionChinese Center for Disease Control and Prevention

The use of building materials containing naturally occurring radionuclides such as^40K,^238U,^232Th and their progeny, could lead to external exposures to the residents of such buildings. In this paper, a set of models are constructed to calculate the specific effective dose rates（the effective dose rate per Bq/kg of ^40K, the ^238U series,and the ^232Th series） imposed on residents by building materials with the MCNPX code. The effect of chemical composition, position concerned in the room and thickness as well as density of material is analyzed. In order to facilitate more precise assessment of indoor external dose due to gamma-emitting radionuclides in building materials,three regressive expressions are proposed and validated by measured data to calculate specific effective rates for40 K,the238U series and the232 Th series, respectively.

关键词： Monte Carlo specific effective dose rate building materials

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building materials

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China's Refractories 2008年第4期 45-47页

China’s Output of Primary Magnesium During *** *** to the statistical data from China Nonferrous Metals Industry Association,during January to August of 2008,China’s primary magnesium output is 448.9 thousand tons,increasing 16.8% year on *** of each area increased differently:Shandong,Shaanxi and Ningxia are 238.5,60.3 and 48.9 thousand tons,increasing 4.44%,55.41% and 22.63%,respectively.

关键词： CNY building materials

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building materials

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China's Refractories 2008年第3期 48-49页

About 1/3 Increase of China’s Ceramic Production CostIt was reported by Foshan Ceramics Industry Association that, due to price rising of raw materials and crude oil, and short electric supply, the procurement cost of ceramic enterprises increased about 1/3. Due to high production cost, some ceramic enterprises in Fujian and Yunan stopped production.

关键词： CNY building materials high

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The Vascular Vegetation Populating the Flora in building materials of Historic Monuments Cities of the West Central Region of Morocco

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Open Journal of Ecology 2014年第9期4卷 565-570页

作者： Bouamar Baghdad A.Taleb A.Carlo Inigo Inigo H.El Hadi M.Dalimi Department Natural Resources and Environment Agronomic and Veterinary Institute-Hassan ⅡRabatMorocco Instituto de Recursos Naturales y Agrobiologia de Salamanca(IRNASA) Consejo Superior de Investigaciones Cientificas(CSIC)SalamancaSpain Laboratory of Applied Geology Geomatics and EnvironmentFaculty of Science of Ben M’SikHassan Ⅱ UniversityCasablancaMorocco Department of Chemistry Faculty of Science and TechnologyUniversity Hassan ⅡMohammediaMorocco

In the concern of the preservation of the main historic monuments of the cities of Rabat and Sale (Morocco), a botanical study was conducted in 2009. The prospecting of these monuments allowed raising an inventory of the flora populating their building materials, and it has proved that this flora is rich and diversified. Indeed, it consists of 171 adventitious species distributed in 46 botanical families. The most represented families are Asteraceae, Poaceae, Fabaceae, Caryophyllaceae, Geraniaceae, Brassicaceae and Lamiaceae. They supply, to them only 49.7% of the specific size. The annual therophytes and the dicotyledon are dominant with respectively 66.7% and 84.7% of the specific size. Nevertheless, the presence of more than 20 species of trees and perennials constitutes a serious danger for bulwarks walls, especially by the phenomenon of fissuring by the action of the huge roots of these vegetables. These vegetables fitting into are placed on joints or cracks fissures have a chemical action on stones by acids that they release, and also a mechanical action by the growth of roots inside cracks fissures. They remain one of these are one of the important biological factors of the degradation of historic monuments. It is to note that the bulwarks walls of the site of Chella (Roman ruins) present more floral diversity than the other canvassed monuments (91 species) that are 53% of the total size.

关键词： Degradation Historic Monuments building materials Flora Morocco

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