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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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Natural Radioactivity Measurements for Some Algerian building materials

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Journal of Physical Science and Application 2012年第6期2卷 171-174页

作者： Abdelfettah Belafrites Ahmed Tedjani Radiation Physics and Applieations Laboratory (RPAL) University of Jijel Jijel 18000 Algeria

The objective of this work is to assess the radiation hazards associated gamma rays from building materials. Natural gamma rays activities of natural radionuclide represented mainly by three natural radioactive series ^238U, ^235U and ^232Th, and the primordial ^40K in the samples of building materials which consist of bricks, ceramics, marble and gypsum from different areas of eastern Algeria are measured using gamma ray spectrometry. The values of the activities of these radionuclides do not clearly reflect the radiation hazard associated with these materials. Therefore, the radium equivalent （Raeq） concentration is defined taking into account the effectiveness of these isotopes in creating the radiation hazard. Radium equivalent activities, external and internal hazard indices （Hex and Hin） are calculated from the activities of ^226Ra, ^232Th and ^40K for suitability of the materials.

关键词： Natural radioactivity building materials y-ray spectrometry.

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The Curriculum Reform Strategy of building materials in Higher Vocational Colleges Under the Background of"Three Educations"Reform

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Journal of Contemporary Educational Research 2022年第2期6卷 5-8页

作者： Jing Sun Chongqing Energy College Chongqing 402260China

With the deepening of the"three educations"reform,it has been emphasized that higher vocational colleges should strengthen the improvement of talent training strategies,improve the school-running quality,and explore from three aspects(teachers,teaching materials,and teaching methods)to improve the teaching efficiency and *** the teaching contents of building materials in higher vocational colleges as the research idea,this paper analyzes the current situation of the curriculum reform under the background of"three educations"reform and explores the corresponding reform strategies.

关键词： "Three educations"reform Higher vocational education building materials Curriculum reform Reform strategy

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Development of a procedure for estimating the parameters of mechanistic VOC emission source models from chamber testing data

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building Simulation 2021年第2期14卷 269-282页

作者： Zhenlei Liu Andreas Nicolai Marc Abadie Menghao Qin John Grunewald Jianshun Zhang Department of Mechanical and Aerospace Engineering Syracuse UniversitySyracuseUSA Dresden University of Technology DresdenGermany University of La Rochelle La RochelleFrance Technical University of Denmark Kongens LyngbyDenmark School of Architecture and Urban Planning Nanjing UniversityNanjingChina

In order to evaluate the impacts of volatile organic compounds(VOCs)emissions from building materials on the indoor air quality beyond the standard chamber test conditions and test period,mechanistic emission source models have been developed in the ***,very limited data are available for the required model parameters including the initial concentration(C_(m0)),in-material diffusion coefficient(D_(m)),partition coefficient(Kma),and convective mass transfer coefficient(k_(m)).In this study,a procedure was developed for estimating the model parameters by using VOC emission data from standard small chamber *** the procedure,initial values of the model parameters were refined by multivariate regression analysis of the measured emission *** verify the procedure and estimate its uncertainty,simulated chamber test data were generated by adding 10% experimental uncertainties on the theoretical curve from the analytical solution to a mechanistic emission *** the procedure was applied to the generated data to estimate the model *** indicated that estimates converged to the original parameter values used for the data generation and the error of estimated parameters D_(m1)C_(m0) and K_(ma) were within±10%,±23%,and±25%of the true values,*** procedure was further demonstrated by applying it to estimate the model parameters from real chamber test *** application of the procedure would result in a database of mechanistic source model parameters for assessing the impact of VOC emissions on indoor pollution load,which are essential input data for evaluating the effectiveness of various indoor air quality(IAQ)design and control strategies as well as the energy required for meeting given IAQ requirements.

关键词： building materials volatile organic compounds(VOCs) emission source model indoor air quality building energy efficiency

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Maximizing deviation method for multiple attribute decision making under q-rung orthopair fuzzy environment

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Defence Technology（防务技术） 2020年第5期16卷 1073-1087页

作者： Jie Wang Gui-wu Wei Cun Wei Jiang Wu School of Business Sichuan Normal UniversityChengdu610101PR China School of Statistics Southwestern University of Finance and EconomicsChengdu611130PR China

Because of the uncertainty and subjectivity of decision makers in the complex decision-making environment,the evaluation information of alternatives given by decision makers is often fuzzy and *** a generalization of intuitionistic fuzzy set(IFSs)and Pythagoras fuzzy set(PFSs),q-rung orthopair fuzzy set(q-ROFS)is more suitable for expressing fuzzy and uncertain ***,in actual multiple attribute decision making(MADM)problems,the weights of DMs and attributes are always completely unknown or partly known,to date,the maximizing deviation method is a good tool to deal with such ***,combine the q-ROFS and conventional maximizing deviation method,we will study the maximizing deviation method under q-ROFSs and q-RIVOFSs in this ***,we briefly introduce the basic concept of q-rung orthopair fuzzy sets(q-ROFSs)and q-rung interval-valued orthopair fuzzy sets(q-RIVOFSs).Then,combine the maximizing deviation method with q-rung orthopair fuzzy information,we establish two new decision making *** this basis,the proposed models are applied to MADM problems with q-rung orthopair fuzzy *** with existing methods,the effectiveness and superiority of the new model are *** method can effectively solve the MADM problem whose decision information is represented by q-rung orthopair fuzzy numbers(q-ROFNs)and whose attributes are incomplete.

关键词： Multiple attribute decision making(MADM) q-rung orthopair fuzzy sets(q-ROFSs) q-rung interval-valued orthopair fuzzy sets (q-RIVOFSs) Maximizing deviation method building materials

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Assessment of Indoor and Outdoor Radon Levels in South Lebanon

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International Journal of Disaster Risk Science 2014年第3期5卷 214-226页

作者： Mohammed A.Kobeissi Omar El Samad Khaled Zahraman Ibrahim Rachidi Lebanese Atomic Energy Commission National Council for Scientific ResearchRiad ElsolhBeirutLebanon Department of Physics Faculty of Sciences(I)The Lebanese UniversityHadethBeirutLebanon

The presence of high indoor radon concentrations,Cx,is a major concern of the public *** of indoor radon in South Lebanon have been achieved using CR-39 *** ranged between 30 and 122 Bq m-3 in one of the major towns in the area and are compared with measured atmospheric air *** seasonal variation of Cxindoors has been observed,although 90%of the obtained indoor Cxmeasurements are below 100 Bq *** homes produced Cxreadings above the permissible *** showed that the ventilation effect played a major factor in reducing radon concentration levels *** assessment has been *** effective doses of radon varied from 1.01±0.10 to 8.65±0.50 m Sv a-1 in six homes in one of the four cases *** dosage values are above the permitted limit of 2.5 m Sv *** types of granite contained in the studied homes were identified and their contributions to radon levels indoors were calculated.

关键词： building materials CR-39 Effective dose Granite exhalation rate Lebanon Radon risk assessment

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Enhanced Thermal Performance of Roofing materials by Integrating Phase Change materials to Reduce Energy Consumption in buildings

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Journal of Renewable materials 2021年第3期9卷 495-506页

作者： Chanita Mano Atthakorn Thongtha Department of Physics Faculty of ScienceNaresuan UniversityPhitsanulok65000Thailand

This work focused on characterizing and improving the thermal behavior of metal sheet *** decrease the heat transfer from the roof into a building,we investigated the efficiency of four types of phase change materials,with different melting points:PCMІ,PCM II,PCM III and PCM IV,when used in conjunction with a sheet metal *** exterior metal roofing surface temperature was held constant at 50℃,60℃,70℃and 80℃,using a thermal source(halogen lights)for 360 min to investigate and compare the thermal performance of the metal sheet roofing with and without phase change materials for each *** thermal behaviors of the phase change materials were analyzed by differential scanning calorimeter(DSC).The results showed the melting points of PCMІ,PCM II,PCM III and PCM IV were around 45℃,50℃,55℃and 59℃,*** integration of PCM IV into the metal roofing sheet increased the thermal performance by reducing the room temperature up to 2.8%,1.4%,1.0%and 0.7%when compared with the normal metal roof sheet,at the controlled temperatures of 50℃,60℃,70℃and 80℃,*** thermal absorption of the phase change materials also caused a time delay in the model room reaching a steady *** integration of phase change materials with metal roofing sheets resulted in better thermal performance and conservation of electrical energy by reducing the demand for cooling.

关键词： Roof metal sheets phase change materials energy saving thermal storage building materials

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Effects of GH Admixture on the Early Strength of Fly Ash Concrete and Mortar

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Journal of Wuhan University of Technology(materials Science) 2008年第5期23卷 755-760页

作者：亢景付 School of Civil Engineering Tianjin University

The enhancement effects of GH admixture on the early strengths of fly ash concrete and mortar were studied, and the mechanism was analyzed by X-ray diffraction （XRD） and scanning electro microscope （SEM）. Experimental results show that, by the incorporation of GH admixture, both of cement hydration and pozzolanic reaction of fly ash are accelerated, the strengths of fly ash concrete and mortar are enhanced noticeably, especially the early strength. With a mixture design of 200 kg/m^3 OPC （Ordinary Portland Cement ）, 200 kg/m^3 fly ash and 50 kg/m^3 GH admixture, the strength of concrete at 1 d, 3 d and 28 d reaches 25 MPa, 50 MPa and 70 MPa respectively.

关键词： building materials fly ash concrete GH admixture strength microstructure

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Preparation and Characterization of Sandwich Structured materials with Interesting Insulation and Fire Resistance

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Journal of Renewable materials 2022年第8期10卷 2029-2039页

作者： Haizhu Wu Jinxing Li Shouhu Bao Fuxian Yang Jun Zhang Hisham Essawy Guanben Du Xiaojian Zhou Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products Southwest Forestry UniversityKunming650224China Department of Polymers and Pigments National Research CentreCairo12622Egypt

A cellular material in the form of 3-layered sandwich structure material was prepared via sole use of mechanical stirring without any use of a foaming agent,while Tween-80 was employed as a foam stabilizer via a developed in-situ mold *** resulting structure displayed a good appearance with no visual *** 3-layered composition of the sandwish structure,“nonporous resin layer-porous foam layer-nonporous resin layer”,was examined in terms of the microstructure,density&density distribution,pulverization ratio,mechanical strength,insulation and flame retardant *** was indicated from the results that the bonding between the resin layer and foam layer was tight,while the tensile rupture always occurred in the porous ***,the density of the sandwich structure material was symmetrical with“saddle”distribution,and a uniform density for any given *** increase in the density at the interface layer provided a good interpretation for the tensile rupture never occurred at the *** brittleness resistance of the developed material was significantly improved,and the pulverization ratio was sharply decreased from 9.93%to 0.31%.The material acquired a thermal conductivity and limiting oxygen index(LOI)of 0.0241 W/m⋅K and 29.92%,respectively,indicating potential use of such materials broadly in fields of insulation and flame retardancy.

关键词： building materials tannin resin sandwich structure insulation fire resistance

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Deep Learning-Based Swot Analysis in Construction and Demolition Waste Management

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Intelligent Automation & Soft Computing 2023年第5期36卷 1497-1506页

作者： R.Rema N.Nalanth Department of Civil Engineering Noorul Islam UniversityThuckalay629180TamilnaduIndia

Researchers worldwide have employed a varied array of sources to cal-culate the successful management of Construction and Demolition(C&DW).Limited research has been undertaken in the domain of Construction and Demoli-tion Waste Management(C&DWM)and consequently leaving a large gap in the availability of effective management *** to the limited time available for building removal and materials collection,preparing for building materials reuse at the end of life is frequently a challenging *** this research work Con-volutional Neural Network-Long Short-Term Memory(CNN-LSTM)is proposed to predict the number of waste materials that are obtained from a building at the end of its useful *** a result,an effective Waste Management(WM)plan has been established through SWOT *** results of the study reveal that,given fundamental building characteristics,it is possible to predict the number of materials that would be collected with high precision from a building after *** proposed deep learning models achieved an average R-squared value of 0.98 and a Mean Absolute Error of 18.1 and 20.14 better than existing methods such as random forest,CNN,and DBN(Data Bus Network).

关键词： Waste management deep learning building materials strengths weaknesses opportunities threats analysis

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