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Synthesis and Characterization of Indium Niobium Oxide Thin Films via Sol—Gel Spin Coating Method

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Journal of Materials Science & Technology 2013年第10期29卷 923-928页

作者： saeed mohammadi mohammad Reza Golobostanfard Hossein Abdizadeh School of Metallurgy and Materials Engineering College of EngineeringUniversity of Tehran Center of Excellence for High Performance Materials University of Tehran

In the present study, niobium-doped indium oxide thin films were prepared by sol-gel spin coating technique. The effects of different Nb-doping contents on structural, morphological, optical, and electrical properties of the films were characterized by means of X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, atomic force microscopy （AFM）, UV-Vis spectroscopy, and four point probe methods. XRD analysis confirmed the formation of cubic bixbyite structure of In203 with a small shift in major peak position toward lower angles with addition of Nb. FESEM micrographs show that grain size decreased with increasing the Nb-doping content. Optical and electrical studies revealed that optimum opto-electronic properties, including minimum electrical resistivity of 119.4 × 10^-3 Ω cm and an average optical transmittance of 85% in the visible region with a band gap of 3.37 eV were achieved for the films doped with Nb-doping content of 3 at.%. AFM studies show that addition of Nb at optimum content leads to the formation of compact films with smooth surface and less average roughness compared with the prepared ln2O3 films.

关键词： Indium oxide Nb-doping Sol-gel spin coating Transparent conductive oxide Opto-electronic properties

Effects of operating parameters on oxidative coupling of methane over Na-W-Mn/SiO_2 catalyst at elevated pressures

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Journal of Natural Gas Chemistry 2011年第2期20卷 204-213页

作者： Jafar Sadeghzadeh Ahari mohammad Taghi Sadeghi saeed Zarrinpashne Process Simulation and Control Laboratory Chemical Engineering College Iran University of Science and Technology (IUST) Gas Research Division-Research Institute of Petroleum Industry (RIPI)

The effects of operating parameters on oxidative coupling of methane （OCM） over Na-W-Mn/SiO2 catalyst have been studied at elevated pressures of 0.2, 0.3 and 0.4 MPa under low gaseous hourly space velocity （GHSV） and low temperature conditions. Experimental results show that when the operating pressure is increased, C2＋ yield slightly decreases, while the maximum ratio of ethylene to ethane remains unchanged. Moreover, it has been found empirically that increase of pressure does not affect the catalyst behavior permanently, the catalyst recovers its original low pressure performance without hysteresis behavior by reducing the pressure. Under the investigated conditions, when oxygen is completely consumed, the increase of GHSV leads to improvement in C2 selectivity, while C3＋ and COx selectivities decrease slightly. The C2＋ selectivity increases by increase of nitrogen diluent in the feed, but the C3＋ hydrocarbons selectivities decrease with increase of nitrogen since it is possible that further dilution at high pressure may reduce the probability of collision between CH3 and C2＋ hydrocarbons. During the stability test at high pressure, the catalyst performance remains unchanged throughout the 20 h running. The fresh and used catalysts were characterized using XRD, SEM and N2 adsorption-desorption methods. It was found that the phase transformation of the support from α-cristobalite to tridymite and quartz does not have obvious effect on catalyst performance at high pressure.

关键词： operating parameters oxidative coupling of methane Na-W-Mn/SiO2 catalyst elevated pressure

Impact of recycling improvement on the life cycle of phosphorus

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Chinese Journal of Chemical Engineering 2019年第5期27卷 1219-1229页

作者： mohammad El Wali saeed Rahimpour Golroudbary Andrzej Kraslawski School of Engineering Sciences Industrial Engineering and Management (IEM)Lappeenranta University of TechnologyP.O. Box 20Fl-53851 LappeenrantaFinland Faculty of Process and Environmental Engineering Lodz University of Technologyul. Wolczanska 27390-924 LodzPoland

Access to natural resources is increasingly more difficult and more costly, partly due to their economic significance and to continuous increase of their global consumption in the recent years. In the case of phosphorus (P), which is a critical raw material, geological distribution of its primary nonrenewable source (phosphate rock) is concentrated in particular regions leading to high supply risk of this raw material. In Europe (EU-28), where phosphate rock reserves are scarce, import of phosphorus has been the main source of supply. It means that Europe relies highly on the foreign exporters. From decision makers' perspective, recycling of phosphorus was taken into account as one of the possible solutions to decrease the dependence on imports and extraction of reserves. The question, however, is to what extent does the recycling of phosphorus help in reducing the reliance on typical supply resources? Hence, the main objective of this paper is to quantify the dynamic flow of phosphorus and show potential benefits of its recycling in Europe. This article presents a system dynamics model for representation of the element P flow and helps to quantify to what extent the recycled phosphorus could mitigate its criticality. Analysis of the results supports previous studies indicating the high reliance ofEU on P imports, estimating around 96% as the reliance percentage on imports. The results imply that improving P recycling has the potential to decrease the level of P imports to a certain extent, which may reach 79%.

关键词： Critical material Phosphorus Dynamic modelling Dynamic simulation Recovery Recycling

Synchronization of two different chaotic systems using Legendre polynomials with applications in secure communications

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Frontiers of Information Technology & Electronic Engineering 2018年第9期19卷 1180-1190页

作者： saeed KHORASHADIZADEH mohammad-Hassan MAJIDI Faculty of Electrical and Computer Engineering University of Birjand Faculty of Electrical and Computer Engineering University of Birjand

In this study, a new controller for chaos synchronization is proposed. It consists of a state feedback controller and a robust control term using Legendre polynomials to compensate for uncertainties. The truncation error is also considered. Due to the orthogonal functions theorem, Legendre polynomials can approximate nonlinear functions with arbitrarily small approximation errors. As a result, they can replace fuzzy systems and neural networks to estimate and compensate for uncertainties in control systems. Legendre polynomials have fewer tuning parameters than fuzzy systems and neural networks. Thus, their tuning process is simpler. Similar to the parameters of fuzzy systems, Legendre coefficients are estimated online using the adaptation rule obtained from the stability analysis. It is assumed that the master and slave systems are the Lorenz and Chen chaotic systems, respectively. In secure communication systems, observer-based synchronization is required since only one state variable of the master system is sent through the channel. The use of observer-based synchronization to obtain other state variables is discussed. Simulation results reveal the effectiveness of the proposed approach. A comparison with a fuzzy sliding mode controller shows that the proposed controller provides a superior transient response. The problem of secure communications is explained and the controller performance in secure communications is examined.

关键词： Observer-based synchronization Chaotic systems Legendre polynomials Secure communications

Centrifuge model test and numerical interpretation of seismic responses of a partially submerged deposit slope

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第2期12卷 381-394页

作者： Zhiliang Sun Lingwei Kong Aiguo Guo mohammad alam State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

Partially submerged deposit slopes are o ften encountered in practical engineering *** r,studies on evaluating their stability under seismic loading are still *** order to understand the seismic behavior of partially submerged deposit slopes,centrifuge shaking table model tests(50 g) were *** responses of horizontal accelerations,accumulated excess pore pressures,deformation mode,and failure mode of the partially submerged deposit slope model were *** dynamic centrifuge model tests,EQ5 shaking event was applied *** results indicated that in the saturated zone of the deposit slope,liquefaction did not occur,and the measured horizontal accelerations near the water table were amplified as a layer-magnification *** was also shown that the liquefaction-resistance of the deposit slope increased under multiple sequential ground motions,and the deformation depth of the deposit slope induced by earthquake increased gradually with increasing dynamic Ioad *** for the excessive crest settlement generated by strong shaking,an additional vertical permanent displacement was initiated at the slope crest due to the dissipation of excess pore pressure under seismic *** result of particle image velocimetry(PIV) analysis showed that an obvious internal arc-slip was generated around the water table of the partially submerged deposit slope under seismic loading.

关键词： Centrifuge model test Acceleration responses Excess pore pressure Deposit slope

A Unified Computational Method for Simulating Dynamic Behavior of Planing Vessels

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China Ocean Engineering 2009年第3期23卷 517-528页

作者： mohammad saeed SEIF Ebrahim JAHANBAKHSH Roozbeh PANAHI mohammad Hossein KARIMI Sharif University of Technology Transportation Research Institute

High speed planing hulls have complex hydrodynamic behaviors. The trim angle and drafts are very sensitive to speed and location of the center of gravity. Therefore, motion simulation for such vessels needs a strong coupling between rigid body motions and hydrodynamic analysis. In addition, free surface should be predicted with good accuracy for each time step. In this paper, velocity and pressure fields are coupled by use of the fractional step method. On the basis of in- tegration of the two-phase viscous flow induced stresses over the hull, acting loads （forces and moments） are calculated. With the strategy of boundary-fitted body-attached mesh and calculation of 6-DoF motions in each time step, time history of ship motions including displacements, speeds and accelerations are evaluated. For the demonstration of the software capabilities, circular cylinder slamming is simulated as a simple type of water slamming. Then, a high-speed planing catamaran is investigated in the case of steady forward motion. All of the results are in good concordance with experimental data. The present method can be widely implemented in design as well as in the performance prediction of high-speed vessels.

关键词： ship motions slamming planing vessel

Prediction of machining chatter in milling based on dynamic FEM simulations of chip formation

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Advances in Manufacturing 2018年第3期6卷 334-344页

作者： Ehsan Jafarzadeh mohammad R. Movahhedy saeed Khodaygan mohammad Ghorbani Precision Manufacturing Laboratory Department of Mechanical Engineering Sharif University of TechnologyAzadi Avenue Tehran Iran

Chatter vibration is a major obstacle inachieveing increased machining performance. In thisresearch, a finite element model of chip formation in a 2Dmilling process is used to predict the occurrence of chattervibrations, and to investigate the effects of variousmachining parameters on this phenomenon. The dynamicproperties of the machine tool at the tool tip are obtainedbased on experimental modal analysis, and are used in themodel as the cutter dynamics. The model allows for thenatural development of vibration as the result of the chip-tool engagement, and accounts for various phenomena thatoccur at the chip-tool interface ultimately leading tostable or unstable cutting. The model was used todemonstrate the effects of the machining parameters, suchas the axial depth of cut, radial immersion, and feed rate,on the occurrence of chatter. Additionally, the phenomenonof jumping out of the cut region could be observed in thismodel and its effect on the chatter process is *** numerical model is verified based on comparisons withexperimental results.

关键词： Machining chatter Milling Finite elementmodel (FEM) simulation Feed rate

Facile synthesis of nanoporous CuS nanospheres for high-performance supercapacitor electrodes

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Journal of Energy Chemistry 2017年第4期26卷 762-767页

作者： Hamid Heydari Seyyed Ebrahim Moosavifard mohammad Shahraki saeed Elyasi Faculty of Sciences Razi UniversityKermanshahIran Young Researchers and Elite Club Central Tehran BranchIslamic Azad UniversityTehranIran Department of Chemistry University of Sistan and BaluchestanZahedanIran Department of Chemical Engineering Sharif University of TechnologyTehranIran

In recent years, development of high-performance supercapacitor electrode materials has stimulated a great deal of scientific research. The electrochemical performance of a supercapacitor strongly depends on its material structures. Herein, we report a simple strategy for high-performance supercapacitors by building pseudocapacitive CuS nanospheres with nanoporous structures, nanosized walls（<10 nm） and relatively large specific surface area of 65 m;/g. This electrode demonstrates excellent electrochemical performance including a maximum specific capacitance of 814 F/g at 1 A/g, significant rate capability of 42% capacitance retention at an ultrafast rate of 50 A/g, and outstanding long-term cycling stability at various current densities. The remarkable electrochemical performance of as-prepared nanoporous CuS nanospheres electrode has been attributed to its unique structures that plays a key role in providing short ion and electron diffusion pathways, facilitated ion transport and more active sites for electrochemical reactions. This work sheds a new light on the metal sulfides design philosophy, and demonstrates that nanoporous CuS nanospheres electrode is a promising candidate for application in high-performance supercapacitors.

关键词： Supercapacitor Nanoporous CuS Nanospheres

Environmental degradation through mining for energy resources:The case of the shrinking Laguna Santa Rosa wetland in the Atacama Region of Chile

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Energy Geoscience 2022年第2期3卷 182-190页

作者： mohammad Ayaz alam Rosa Sepúlveda Departamento de Geología Facultad de IngenieríaUniversidad de AtacamaAvenida Copayapu 485CopiapoRegion de AtacamaChile

As the world strives to replace fossil fuels with clean energy e reflected by global surge in the number of electric vehicles e the environmental impact of mining all the lithium(Li)needed to enable such a transformation has become a problem in its own *** South America,the biggest problem is the excessive use of water in Li extraction process in one of the driest areas in the *** from causing severe friction over water rights between local communities and mining companies,it puts enormous pressure on the region's fragile and poorly understood wetland *** are one of the most threatened ecosystems on the Earth,despite their great importance as habitats for a vast number of species and corresponding to one of the most productive *** work is the outcome of an investigation on Laguna Santa Rosa's(LSR)vulnerability resulting from ongoing metal mining operations in its surroundings that require a large volume of water extracted from local aquifers,in addition to a high evaporation rate in the *** groundwater-dependent wetland will soon be further vulnerable with the commencement of water-intensive Li mining at Salar de Maricunga,with the extraction project already having an environmental impact study *** of this wetland protected under the Ramsar Convention and home to numerous wildlife species habiting this highland sector of the Andean Cordillera is vital for the associated *** variation in the water surface area of LSR has been deciphered through the application of a Landsat-5 Thematic Mapper(TM)satellite image *** has been done both for the hydrological year 2016e2017 and 1993-2014 period.A decreasing trend in the water surface area of LSR,a hypersaline lake at the southern extreme of Salar de Maricunga,a salt flat in the Atacama Region of Chile,was observed through the study of satellite images between 1993 and 2014,showing shrinking of this ***,this shrinking t

关键词： Laguna Santa Rosa Salar de Maricunga Lithium Water Wetland Ecosystem