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Improving the Sound Absorption Properties of Flexible Polyurethane (PU) Foam using Nanofibers and Nanoparticles

Sound & Vibration 2019年第5期53卷 207-222页

作者： Roohalah Hajizadeh ali Khavanin mohammad Barmar Ahmad Jonidi jafari Somayeh Farhang Dehghan Department of Occupational Health Engineering Faculty of Medical SciencesTarbiat Modares UniversityTehranIran Department of Polyurethane Iran Polymer and Petrochemical InstituteTehranIran Research Center for Environmental Health Technology Department of Environmental Health EngineeringIran University of Medical SciencesTehranIran Department of Occupational Health and Safety at Work Workplace Health Promotion Research CenterSchool of Public Health and SafetyShahid Beheshti University of Medical SciencesTehranIran

Polyurethane foam as the most well-known absorbent materials has a suitable absorption coefficient only within a limited frequency *** aim of this study was to improve the sound absorption coefficient of flexible polyurethane(PU)foam within the range of various frequencies using clay nanoparticles,polyacrylonitrile nanofibers,and polyvinylidene fluoride *** response surface method was used to determine the effect of addition of nanofibers of PAN and PVDF,addition of clay nanoparticles,absorbent thickness,and air gap on the sound absorption coefficient of flexible polyurethane foam(PU)across different frequency *** absorption coefficient of the samples was measured using Impedance Tubes *** clay at low thicknesses as well as polyacrylonitrile nanofibers and polyvinyl fluoride nanofibers at higher thicknesses had a greater positive effect on absorption *** mean sound absorption coefficient in the composite with the highest absorption coefficient at middle and high frequencies was 0.798 and 0.75,*** comparison with pure polyurethane foam with the same thickness and air gap,these values were 2.22 times at the middle frequencies and 1.47 times at high frequencies,*** porosity rose with increasing nano clay,but decreased with increasing polyacrylonitrile nanofibers and polyvinyl fluoride *** results indicated that the absorption coefficient was elevated with increasing the thickness and air *** study suggests that the use of a combination of nanoparticles and nanofibers can enhance the acoustic properties of flexible polyurethane foam.

关键词： Sound absorption coefficient flexible polyurethane foam nano clay polyacrylonitrile nanofibers polyvinyl fluoride nanofibers

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QUASI-PERMUTATION REPRESENTATIONS OF ALTERNATING AND SYMMETRIC GROUPS

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Acta Mathematica Scientia 2007年第2期27卷 297-300页

作者： Houshang Behravesh mohammad Hossein jafari Department of Mathematics University of Urmia UrmiaIran Department of Mathematics University of Tabriz TabrizIran

The quantities c（G）, q（G） and p（G） for finite groups were defined by H. Behravesh. In this article, these quantities for the alternating group An and the symmetric group Sn are calculated. It is shown that c（G... 详细信息

关键词： Quasi-permutation representations alternating groups symmetric groups character theory

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A survey of incidental ocular trauma by pencil and pen

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International Journal of Ophthalmology(English edition) 2018年第10期11卷 1668-1673页

作者： Seyed ali Tabatabaei mohammad Soleimani Morteza Naderan aliasghar Ahmadraji mohammad Bagher Rajabi Hajar jafari Mona Safizade Department of Ophthalmology Eye Research Center Farabi Eye Hospital Tehran University of Medical Sciences

AIM：To determine characteristic features of ocular trauma resulted from self-trauma by writing instruments among pediatric ***：Thirty-six children who suffered from selfinflicted ocular trauma with a writing instrument were included in this prospective cross-sectional ***：The mean age was 5.6±2.7y with male：female ratio of *** right eye was involved two times more than the left *** superomedial（55.5%）and inferomedial（30.6%）quadrants were the most common sites of *** leading culprit was colored pencils（44.4%）.During surgical exploration,no foreign body（FB）was found in 25（69.4%）patients while an FB was found in 11（30.5%）*** injury was present in two patients（5.6%）and only in superomedial quadrant *** 1 was the most common site for ocular trauma associated with penetrating *** mean ocular trauma score（OTS）in penetrating injuries was 3.8±*** best corrected visual acuity（BCVA）was 0.3±0.6 upon admittance and 0.08±0.21 after one *** final BCVA was significantly correlated with the entrance site,better final BCVA was found in nasal entrance site（P〈0.05）.CONCLUSION：The ophthalmologists should keep a high index of suspicion to rule out penetrating eye injuries related to writing instruments in a young uncooperative *** injury is a life-threatening event that should be ruled out by appropriate *** canthal area as the most common site needs an especial attention in writing instrument injuries.

关键词： pencil pediatric children trauma ocular

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Evaluation of the Relationship between Blocking Patterns and Duration of Spring Frost Waves:The Case of Iran

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Journal of Meteorological Research 2020年第3期34卷 586-600页

作者： Farzaneh jafari HOMBARI Gholamreaza BARATI mohammad MORADI Department of Physical Geography Faculty of Earth SciencesUniversity of Shahid BeheshtiTehran ***Iran Iran Meteorological Organization Tehran ***Iran

In order to evaluate the effects of blocking patterns on the duration of frost waves across Iran,the minimum daily temperatures of 60 weather stations were collected from 20 March 1968 to 21 June *** findings,which were obtained based on the distribution tables of reported temperatures and their frequency variation graphs,resulted in identifying 114 frost *** obtained the daily weather maps at 500 hPa from NCEP/NCAR during the peak days of durable frosts,and it was revealed that the formation of low pressures over 20°-70°E and the dominant southwest-northeast troughs at 500 hPa facilitated the influx of cold air from both eastern Europe and central Siberia toward Iran,leading to the average frost duration of 12.4 ***,low-pressure centers appeared in a dipole pattern in northern Iran over Caspian Sea and created durable frosts with an average duration of 15.4 *** effect of omega shaped pattern of the geopotential height on durable frosts demonstrated a sharp difference with two recent patterns leading to the frost occurrence with a 13.3-day duration ***,the slow speed of cold western currents in the rex type of blocking from 30°to 50°N caused durable frosts of 14.3 ***,we found a specific reduction in the frequency of blocking patterns,which has occurred in the past four ***,the blocking and non-blocking patterns cause long-and short-duration frosts over Iran,respectively.

关键词： blocking patterns durable frosts spring season Iran

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Application of perfectly matched layer to soil-foundation interaction analysis

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第4期10卷 753-768页

作者： mohammad Davoodi Abbas Pourdeilami Hosein Jahankhah mohammad Kazem jafari International Institute of Earthquake Engineering and Seismology TehranIran

Despite of the limitation in modeling infinite space, the finite element method(FEM) is one of the most used tools to numerically study the geotechnical problems regarding the capacity of simulating different geometries, conditions and material behaviors. A kind of absorbing layer named perfectly matched layer(PML) has been applied to modeling the radiation damping using FEM, which makes the dynamic analysis of soil-structure interaction more accurate. The PML is capable of absorbing incident waves under any angle and frequency, ensuring them to pass through the model boundaries without *** this context, a new FEM program has been written and the PML formula has been implemented by rewriting the dynamic equation of motion and deriving new properties for the quadrilateral *** analysis of soil-foundation interaction by applying the PML is validated by the evaluation of impedance/compliance functions for different ground conditions. The results obtained from the PML model match the extended mesh results, even though the domain is small enough that other types of absorbing boundaries can reflect waves back to the foundation. The mechanism of the wave propagation in the region shows that the forced vibrations can be fully absorbed and damped by the boundaries surrounded by PMLs which is the role of radiation damping in FEM modeling.

关键词： Perfectly matched layer (PML) Finite element method (FEM) Wave propagation Impedance/compliance

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Phase Stability in Mechanically Alloyed Mg–Ni System Studied by Experiments and Thermodynamic Calculations

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Acta Metallurgica Sinica(English Letters) 2015年第8期28卷 1002-1007页

作者： mohammad Hossein Enayati Fathallah Karimzadeh Soheil Sabooni Majid jafari Department of Materials Engineering Isfahan University of Technology

In this study, microstructural evolution of Mg–Ni alloy during mechanical alloying（MA） was ***, a thermodynamic approach was utilized to predict the most stable phases formed in Mg–Ni alloy after MA. The phase composition and microstructural properties of Mg–Ni alloy were assessed by X-ray diffractometry, high-resolution field emission scanning electron microscopy and high-resolution transmission electron microscopy. The results showed that ball milling of magnesium and nickel powder mixture for 70 h yields nanostructural Mg2Ni compound with an average grain size of ~20 nm. Thermodynamic calculations revealed that in the composition ranges of 0.0 ／ XMg／ 0.03（at.%）and 0.97 ／ XMg／ 1, there is no driving force for amorphous phase formation. In the composition range of 0.07 ／ XMg／ 0.93, the change of Gibbs free energy for amorphous phase formation was more negative than solid *** for XMg= 0.66（nominal composition of Mg2Ni intermetallic phase）, the change of Gibbs free energy for intermetallic phase was found to be more negative than both amorphous and solid solution phases indicating that Mg2Ni intermetallic compound is the most stable phase, in agreement with the experimental observations.

关键词： Mechanical alloying Nanocrystalline Hydrogen storage material Mg2Ni Thermodynamics

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Petrogenesis of Volcanic Rocks in the Khabr-Marvast Tectonized Ophiolite:Evidence for Subduction Processes in the South-Western Margin of Central Iranian Microcontinent

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Acta Geologica Sinica(English Edition) 2009年第5期83卷 884-892页

作者： Azam SOLTANmohammadI mohammad RAHGOSHAY Morteza KHALATBARI-jafari Faculty of Earth Sciences Shahid Beheshti University TehranIran Institute for Earth Sciences Geological Survey of IranTehranIran

The Late Cretaceous Khabr-Marvast tectonized ophiolite is located in the middle part of the Nain-Baft ophiolite belt, at the south-western edge of the central Iranian microcontinent. Although all the volcanic rocks in the study area indicate subduction-related magmatism （e.g. high LILE （large ion lithophile elements） / HFSE （high field strenght elements） ratios and negative anomalies in Nb and Ta）, geological and geochemical data clearly distinguish two distinct groups of volcanic rocks in the tectonized association：（1） group 1 is comprised of hyaloclastic breccias, basaltic pillow lavas, and andesite sheet flows. These rocks represent the Nain-Baft oceanic crust; and （2） group 2 is alkaline lavas from the top section of the ophiolite suite. These lavas show shoshonite affinity, but do not support the propensity of ophiolite.

关键词： alkaline lavas subduction-related magmatism tectonized ophiolite central Iranian microcontinent

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Solving unit commitment problem using a novel version of harmony search algorithm

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Frontiers in Energy 2014年第3期8卷 297-304页

作者： Roozbeh MORSali Tohid jafari Amirhossein GHODS mohammad KARIMI Babol (Noshirvani) University of Technology Babol *** Iran Department of Electrical Engineering Tabriz branch Islamic Azad University Tabriz 157944533 Iran University of Ulsan Ulsan 680749 Republic of Korea Young Researchers and Elite Club Parsabad Moghan Branch Islamic Azad University Parsabad Moghan *** Iran

In this context, a novel structure was proposed for improving harmony search （HS） algorithm to solve the unit comment （UC） problem. The HS algorithm obtained optimal solution for defined objective function by improvising, updating and checking operators. In the proposed improved self-adaptive HS （SGHS） algorithm, two important control parameters were adjusted to reach better solution from the simple HS algorithm. The objective function of this study consisted of operation, start-up and shut-down costs. To confirm the effectiveness, the SGHS algorithm was tested on systems with 10, 20, 40 and 60 generating units, and the obtained results were compared with those of the simple HS algorithm and other related works.

关键词： generation scheduling harmony search (HS)algorithm intelligent technique unit commitment

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Improving the Cellular Characteristics of Aluminum Foam for Maximum Sound Absorption Coefficient Using Genetic Algorithm

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Sound & Vibration 2021年第2期55卷 117-130页

作者： mohammad Javad jafari Mohsen Niknam Sharak ali Khavanin Touraj Ebadzadeh Mahmood Fazlali Rohollah Fallah Madvari Department of Occupational Health Engineering School of Public Health and SafetyShahid Beheshti University of Medical SciencesTehranIran Mechanical Engineering Department of Mechanical EngineeringUniversity of BirjandBirjandIran Department of Occupational Health Engineering Faculty of Medical SciencesTarbiat Modares UniversityTehranIran Department of Ceramics Materials and Energy Research CenterAlborzIran Department of Data and Computer Science Faculty of Mathematical SciencesShahid Beheshti UniversityTehranIran Student Research Committee Department of Occupational Health EngineeringSchool of Public Health and SafetyShahid Beheshti University of Medical SciencesTehranIran Department of Occupational Health School of Public HealthShahid Sadoughi University of Medical SciencesYazdIran

Fabricating of metal foams with desired morphological parameters including pore size,porosity and pore opening is possible now using sintering ***,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 *** sound absorption models such as Lu model describe the relationship between morphological parameters and the sound absorption *** this study,the Lu model was used to optimize the morphological parameters of aluminum metal foam for the best sound absorption *** this purpose,the Lu model was numerically solved using written codes in MATLAB *** validating the proposed codes with benchmark data,the genetic algorithm(GA)was applied to optimize the affecting morphological parameters on the sound absorption *** optimization was carried out for the thicknesses of 5 mm to 40 mm at the sound frequency range of 250 Hz–8000 *** 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 *** result of this study was applied to fabricate the desired aluminum metal foams for the best sound *** novel approach applied in this study,is expected to be successfully applied in for best sound absorption in desired frequencies.

关键词： Acoustic model Genetic Algorithm(GA) metal foam optimization Sound Absorption Coefficient(SAC)

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The Effect of Spironolactone Loading on the Properties of 3D-Printed Polycaprolactone/Gold Nanoparticles Composite Scaffolds for Myocardial Tissue Engineering

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Journal of Bionic Engineering 2024年第2期21卷 924-937页

作者： Sharareh Ghaziof Shahrokh Shojaei Mehdi Mehdikhani mohammad Khodaei Milad jafari Nodoushan Department of Biomedical Engineering Central Tehran BranchIslamic Azad UniversityTehran***Iran Stem Cells Research Center Tissue Engineering and Regenerative Medicine InstituteCentral Tehran BranchIslamic Azad UniversityTehran***Iran Department of Biomedical Engineering Faculty of EngineeringUniversity of IsfahanIsfahan***Iran Materials Engineering Group Golpayegan College of EngineeringIsfahan University of TechnologyGolpayegan87717-67498Iran Hard Tissue Engineering Research Center Tissue Engineering and Regenerative Medicine InstituteCentral Tehran BranchIslamic Azad UniversityTehran***Iran

Engineered cardiac constructs(ECC)aid in the progression of regenerative medicine,disease modeling and targeted drug delivery to adjust and aim the release of remedial combination as well as decrease the side effects of *** this research,polycaprolactone/gold nanoparticles(PCL/GNPs)three-dimensional(3D)composite scaffolds were manufactured by 3D printing using the fused deposition modeling(FDM)method and then coated with gelatin/spironolactone(GEL/SPL).Scanning electron microscopy(SEM)and Fourier transform-infrared spectroscopy(FTIR–ATR)were applied to characterize the ***,drug release,biodegradation,behavior of the myoblasts(H9C2)cell line,and cytotoxicity of the 3D scaffolds were *** microstructural observation of the scaffolds reported interconnected pores with 150–300µm in *** 3D scaffolds were degraded significantly after 28 days of immersion in stimulated body fluid(SBF),with the maximum rate of GEL-coated 3D *** release from cross-linked GEL coating demonstrated the excess of drug release over time,and according to the control release systems,the drug delivery systems(DDS)went into balance after the 14th *** addition,cell culture study showed that with the addition of GNPs,the proliferation of(H9C2)was enhanced,and with GEL/SPL coating the cell attachment and viability were improved *** findings suggested that PCL/GNPs 3D scaffolds coated with GEL/SPL can be an appropriate choice for myocardial tissue engineering.

关键词： Polycaprolactone Gold nanoparticles Drug delivery systems Spironolactone Cell behavior Myoblasts

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