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International Journal of Minerals,Metallurgy and Materials 2013年第5期20卷 450-455页

作者： mohammad Sadegh Shakeri Materials and Energy Research Center (MERC) P.O. Box 31779-83634KarajIran

Crystallization kinetics of metastable B-quartz solid solution as a desirable phase for the production of trans- parent lithium aluminosilicate （LAS） glass ceramics was investigated in the presence of Y203. Accordingly, differential thermal analysis scans were performed thoroughly to study the mechanism of crystallization kinetics. The aim of this investigation is to discover the complicated mechanism of crystallization process in the presence of co-additives and ac- cordingly find a way for increasing the transparency of glass ceramics. It is shown that the bulk （3D） growth is intensively increased by the enhancement of Y203. Then again, reducing nucleation and increasing growth mechanisms were recog- nized for the LAS system in the presence of Y2O3. Results of the investigation illustrate that when co-additives are added to glasses, it is necessary to nucleate the optical component separately before the growth process.

关键词： glass ceramics lithium aluminosilicate yttria crystallization kinetics nanocrystals transparency

Design of an adaptive finite-time controller for synchronization of two identical/different non-autonomous chaotic flywheel governor systems

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Chinese Physics B 2012年第3期21卷 101-111页

作者： mohammad Pourmahmood Aghababa Electrical Engineering Department Urmia University of Technology

The centrifugal flywheel governor （CFG） is a mechanical device that automatically controls the speed of an engine and avoids the damage caused by sudden change of load torque. It has been shown that this system exhibits very rich and complex dynamics such as chaos. This paper investigates the problem of robust finite-time synchronization of non-autonomous chaotic CFGs. The effects of unknown parameters, model uncertainties and external disturbances are fully taken into account. First, it is assumed that the parameters of both master and slave CFGs have the same value and a suitable adaptive finite-time controller is designed. Second, two CFGs are synchronized with the parameters of different values via a robust adaptive finite-time control approach. Finally, some numerical simulations are used to demonstrate the effectiveness and robustness of the proposed finite-time controllers.

关键词： finite-time controller chaos synchronization non-autonomous centrifugal flywheel gov-ernor chaotic system

The sol-gel derived Co-Mn/TiO_2 catalysts for light olefins production

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燃料化学学报 2014年第2期42卷 212-218页

作者： mohammad Mehdi Khodaei Mostafa Feyzi Jahangir Shahmoradi mohammad Joshaghani Faculty of Chemistry Razi University

在这个研究工作，二 30%(Co-Mn )/TiO2 催化剂用大音阶的第五音胶化(催化剂 A ) 和一起沉淀(催化剂 B ) 被准备方法。到在 Fischer-Tropsch 合成(英尺) 的 C24 轻石蜡的活动和选择在不同运作的条件下面在一个改正床反应堆被学习了。这... 详细信息

在这个研究工作，二 30%(Co-Mn )/TiO2 催化剂用大音阶的第五音胶化(催化剂 A ) 和一起沉淀(催化剂 B ) 被准备方法。到在 Fischer-Tropsch 合成(英尺) 的 C24 轻石蜡的活动和选择在不同运作的条件下面在一个改正床反应堆被学习了。这些运作的条件是：温度

关键词： Fischer-Tropsch synthesis light olefins characterization

Ultrasensitive and selective 4-aminophenol chemical sensor development based on nickel oxide nanoparticles decorated carbon nanotube nanocomposites for green environment

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Journal of Environmental Sciences 2017年第3期29卷 27-38页

作者： mohammad Musarraf Hussain Chemistry Department Faculty of ScienceKing Abdulaziz UniversityJeddah 21589P.O.Box 80203Saudi Arabia Center of Excellence for Advanced Material Research(CEAMR) King Abdulaziz UniversityJeddah 21589P.O.Box 80203Saudi Arabia

Nickel oxide nanoparticles decorated carbon nanotube nanocomposites （*** NCs） were prepared in a basic medium by using facile wet-chemical routes. The optical, morphological, and structural properties of *** NCs were characterized using Fourier transformed infra-red （FT-IR）, Ultra-violet visible （UV/Vis） spectroscopy, field-emission scanning electron microscopy （FESEM）, X-ray energy dispersed spectroscopy （XEDS）, X-ray photoelectron spectroscopy （XPS）, and powder X-ray diffraction （XRD） methods. Selective 4-aminophenol （4-AP） chemical sensor was developed by a fiat glassy carbon electrode （GCE, surface area： 0.0316 cm2） fabricated with a thin-layer of NCs. Electrochemical responses including higher sensitivity, large dynamic range （LDR）, limit of detection （LOD）, and long-term stability towards 4-AP were obtained using the fabricated chemical sensors. The calibration curve was found linear （R2 = 0.914） over a wide range of 4-AP concentration （0.1 nmol/L-0.1 tool/L）. In perspective of slope （2 x 10.5 gA/gM）, LOD and sensitivity were calculated as 15.0 ＋ 0.1 pM and -6.33 - 10.4 gA/（***） respectively. The synthesized *** NCs using a wet-chemical method is a significant route for the development of ultrasensitive and selective phenolic sensor based on nano-materials for environmental toxic substances. It is suggested that a pioneer and selective development of 4-AP sensitive sensor using *** NCs by a facile and reliable current us voltage （I-V） method for the major application of toxic agents in biological, green environmental, and health-care fields in near future.

关键词： NiO decorated CNT nanocomposltesOptical evaluationFabricationSensitivity4-AminophenolI-V method

Sources and Ecological Risks of Heavy Metals in Soils Under Different Land Uses in Bangladesh

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Pedosphere 2019年第5期29卷 665-675页

作者： mohammad Saiful ISLAM mohammad Kawser AHMED mohammad Habibullah AL-MAMUN Shah mohammad Asraful ISLAM Department of Soil Science Patuakhali Science and Technology UniversityDumkiPatuakhali 8602 (Bangladesh) Environment and Information Sciences Yokohama National UniversityYokohama 240-8501 (Japan) Department of Oceanography University of DhakaDhaka 1000 (Bangladesh) Department of Fisheries University of DhakaDhaka 1000 (Bangladesh) Department of Plant Pathology Patuakhali Science and Technology UniversityDumkiPatuakhali 8602 (Bangladesh)

Soil heavy metal pollution, influenced by both natural and anthropogenic factors, significantly reduces environmental quality. In this study, Cr, Ni, Cu, As, Cd, and Pb in eight different land-use soils from Patuakhali District in Bangladesh were assessed. Concentrations of Cr, Ni, Cu, As, Cd, and Pb in soils were 1-87, 5-271, 4-181, 0-80, 0.2-24.0, and 5-276 mg kg-1, respectively, measured using an inductively coupled plasma-mass spectrometer. The enrichment factor, pollution load index (PLI), and contamination factor (CJ) of metal i were used to assess the ecological risk posed by metals in soils. The PLI ranged from 0.78 to 2.66, indicating baseline levels to progressive deterioration of soil due to metal contamination. However, C;of Cd ranged from 1.8 to 12.0, which showed that the studied soils were strongly impacted by Cd. Considering the severity of the potential ecological risk of a single metal, the descending order was Cd > As > Pb > Cu > Ni > Cr. Soils under all land uses showed moderate to very high potential ecological risk.

关键词： Cd contamination factor degree of contamination enrichment factor environmental quality pollution load index soil deterioration soil pollution

Seismic analysis of semi-sine shaped alluvial hills above subsurface circular cavity

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Earthquake Engineering and Engineering Vibration 2020年第4期19卷 903-917页

作者： Mehdi Panji mohammad Habibivand Department of Civil Engineering Zanjan BranchIslamic Azad UniversityZanjanIran

In this study, a seismic analysis of semi-sine shaped alluvial hills above a circular underground cavity subjected to propagating oblique SH-waves using the half-plane time domain boundary element method(BEM) was carried out. By dividing the problem into a pitted half-plane and an upper closed domain as an alluvial hill and applying continuity/boundary conditions at the interface, coupled equations were constructed and ultimately, the problem was solved step-by-step in the time domain to obtain the boundary values. After solving some verification examples, a semi-sine shaped alluvial hill located on an underground circular cavity was successfully analyzed to determine the amplification ratio of the hill surface. For sensitivity analysis, the effects of the impedance factor and shape ratio of the hill were also considered. The ground surface responses are illustrated as three-dimensional graphs in the time and frequency domains. The results show that the material properties of the hill and their heterogeneity with the underlying half-space had a significant effect on the surface response.

关键词： alluvial semi-sine shaped hill half-plane BEM time domain circular cavity SH waves

Mechanical properties and microstructural evolution of rheocast A356 semi-solid slurry prepared by annular electromagnetic stirring

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China Foundry 2023年第4期20卷 315-328页

作者： mohammad Taghi Asadi Khanouki Department of Materials and Metallurgy Engineering Shahid Bahonar University of KermanP.O.Box ***KermanIran Mineral Industries Research Center(MIRC) Shahid Bahonar University of KermanP.O.Box ***KermanIran

Nowadays,having an effective technique in preparing semi-solid slurries for rheocasting process seems to be an essential *** this study,semi-solid slurry of A356 aluminum alloy was prepared by three-phase annular electromagnetic stirring(A-EMS)technique under different *** effects of stirring current,pouring temperature and stirring time on microstructural evolution,mean particle size,shape factor and solid fraction were *** rheocasting process was carried out by using a drop weight setup and to inject the prepared semi-solid slurry in optimal conditions into the step-die *** filling behavior and mechanical properties of parts were *** evolution showed that the best semi-solid slurry which had fine spherical particles with the average size of~27μm and a shape factor of~0.8 was achieved at the stirring current of 70 A,melt pouring temperature of 670℃,and stirring time of 30 *** these conditions,the step-die cavity was completely filled at die preheating temperature of 470℃.The hardness increases by decreasing step thickness as well as die preheating ***,the tensile properties are improved at lower die preheating *** fracture surface,which consists of a complex topography,indicates a typical ductile fracture.

关键词： semi-solid slurry annular electromagnetic stirring rheocast A356 aluminum alloy microstructural evolution mechanical properties magnetic flux density

Generation of endurance time excitation functions using spectral representation method

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Earthquake Engineering and Engineering Vibration 2023年第2期22卷 441-452页

作者： Parsa Parvanehro mohammad Safi Faculty of Civil Water and Environmental EngineeringShahid Beheshti UniversityTehran ***Iran

In this study,application of the spectral representation method for generation of endurance time excitation functions is *** this method,the intensifying acceleration time series is generated so that its acceleration response spectrum in any desired time duration is compatible with a time-scaled predefined acceleration response *** this purpose,simulated stationary acceleration time series is multiplied by the time dependent linear modulation function,then using a simple iterative scheme,it is forced to match a target acceleration response *** is shown that the generated samples have excellent conformity in low frequency,which is useful for nonlinear endurance time *** the second part of this study,it is shown that this procedure can be extended to generate a set of spatially correlated endurance time excitation *** makes it possible to assess the performance of long structures under multi-support seismic excitation using endurance time analysis.

关键词： endurance time analysis endurance time excitation functions spatial variation of seismic ground motions multi-support excitation spectral representation method

On Solvability of Groups with a Few Non-cyclic Subgroups

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Algebra Colloquium 2016年第1期23卷 105-110页

作者： mohammad Zarrin Department of Mathematics University of Kurdistan P.O. Box 416 Sanandaj Iran

Li and Zhao studied groups with a few conjugacy classes of non-cyclic subgroups. In this paper we study groups with a few non-cyclic subgroups. In fact, among other things, we give some sufficient conditions on the nu... 详细信息

关键词： solvable group simple group

Slender reinforced concrete shear walls with high-strength concrete boundary elements

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Frontiers of Structural and Civil Engineering 2023年第1期17卷 138-151页

作者： mohammad SYED Pinar OKUMUS Department of Civil Structural and Environmental EngineeringUniversity at BuffaloBuffaloNY 14260USA

Reinforced concrete structural walls are commonly used for resisting lateral forces in buildings. Owing to the advancements in the field of concrete materials over the past few decades, concrete mixes of high compressive strength, commonly referred to as high-strength concrete (HSC), have been developed. In this study, the effects of strategic placement of HSC on the performance of slender walls were examined. The finite-element model of a conventional normal-strength concrete (NSC) prototype wall was validated using test data available in extant studies. HSC was incorporated in the boundary elements of the wall to compare its performance with that of the conventional wall at different axial loads. Potential reductions in the reinforcement area and size of the boundary elements were investigated. The HSC wall exhibited improved strength and stiffness, and thereby, allowed reduction in the longitudinal reinforcement area and size of the boundary elements for the same strength of the conventional wall. Cold joints resulting from dissimilar concrete pours in the web and boundary elements of the HSC wall were modeled and their impact on behavior of the wall was examined.

关键词： slender walls high-strength concrete rectangular and barbell-shaped walls cold joints