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3篇 您的检索式:作者名="Rohollah Fallah Madvari"
    题名 作者 年代 出处 被引量
1Improving the Cellular Characteristics of Aluminum Foam for Maximum Sound Absorption Coefficient Using Genetic Algorithm显示文摘Fabricating of metal foams with desired morphological parameters including pore size,porosity and pore opening is possible now using sintering technology.Thus,if it is possible to determine the morphology of metal foam to absorb sound at a given frequency,and then fabricate it through sintering,it is expected to have optimized metal foams for the best sound absorption.Theoretical sound absorption models such as Lu model describe the relationship between morphological parameters and the sound absorption coefficient.In this study,the Lu model was used to optimize the morphological parameters of aluminum metal foam for the best sound absorption coefficient.For this purpose,the Lu model was numerically solved using written codes in MATLAB software.After validating the proposed codes with benchmark data,the genetic algorithm(GA)was applied to optimize the affecting morphological parameters on the sound absorption coefficient.The optimization was carried out for the thicknesses of 5 mm to 40 mm at the sound frequency range of 250 Hz–8000 Hz.The optimized parameters ranged from 50%to 95%for porosity,0.1 mm to 4.5 mm for pore size,and 0.07 mm to 0.6 mm for pore opening size.The result of this study was applied to fabricate the desired aluminum metal foams for the best sound absorption.The novel approach applied in this study,is expected to be successfully applied in for best sound absorption in desired frequencies.Mohammad Javad Jafari Mohsen Niknam Sharak Ali Khavanin Touraj Ebadzadeh Mahmood Fazlali Rohollah Fallah Madvari 2021Sound & Vibration2021,55,2:0
2Analytical Study on the Rate of Sound Transmission Loss in Single Row Honeycomb Sandwich Panel Using a Numerical Method显示文摘Honeycomb structures have recently,replaced with conventional homogeneous materials.Given the fact that sandwich panels containing a honeycomb core are able to adjust geometric parameters,including internal angles,they are suitable for acoustic control applications.The main objective of this study was to obtain a transmission loss curve in a specific honeycomb frequency range along with same overall dimensions and weight.In this study,a finite element model(FEM)in ABAQUS software was used to simulate honeycomb panels,evaluate resonant frequencies,and for acoustic analysis.This model was used to obtain acoustic pressure and then to calculate the sound transmission loss(STL)in MATLAB software.Vibration and acoustic analysis of panels were performed in the frequency range of 1 to 1000 Hz.The models analyzed in this design includes 14-single row-honeycomb designs with angles of−45°,−30°,−15°,0°,+15°,+30°,+45°.The results showed that a-single row and−45°cell angle honeycomb panel in the frequency range of 1 to 1000 Hz had the highest STL as well as the highest number of frequency modes(90 mods).Furthermore,the panel had the highest STL regarding the area under the STL curve(dB∙Hz).The panels containing more frequency mods,have a higher transmission loss.Moreover,the sound transmission loss is more sensitive to the cell angle variable(θ).In other studies,the STL was more sensitive to the number of honeycomb cells in the horizontal and vertical directions,as well as the angle of cells.Rohollah Fallah Madvari Mohammad Reza Monazzam Mohsen Niknam Sharak Mohsen Mosa Farkhani 2020Sound & Vibration2020,54,2:0
3Application of the BASNEF Model in Safety Training in Automobile Manufacturing Plants显示文摘After controls,including engineering and management,thefinal way to control noise is to use hearing protection devices.Duetothelack ofastandardized questionnaireregarding investigatingworkers’use of hearing protection devices on the basis of the BASNEF behavioral model,the present study was conducted to investigate the effect of health education based on the BASNEF model on the use of hearing protection devices in workers of an auto-mobile manufacturing plant in Iran.This quasi-experimental and prospective intervention study was performed on 80 workers at an automobile manufacturing plant who are exposed to noise levels above 85 decibels and donot use hearing protection devices.In this study,40 people working in a cast iron foundry were selected as the inter-vention group,and 40 working in aluminum casting were chosen as the control group.Questionnaires were ana-lyzed at the beginning of the intervention and three months after the intervention in the intervention and control groups.There was no significant difference between the intervention and control groups before the intervention.There was a significant difference between the intervention and control groups after the intervention in the area of knowledge.A significant correlation was observed between the intervention and control groups after the inter-vention program in all areas of the BASNEF educational model except behavioral intention.In this study,the effect of educational intervention on the use of hearing protection devices was investigated,and with the educa-tional intervention,it was tried to get help from influential people and enabling factors in education based on the BASNEF model.The results showed that the educational intervention based on the BASNEF model can improve the knowledge of individuals in both the intervention and control groups.Fereydoon Laal Amir Hossein Khoshakhlagh Esmaeil Zarei Rohollah Fallah Madvari Somayeh Farhang Dehghan 2022Sound & Vibration2022,56,4:0
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