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Simultaneous syngas production with different H_2/CO ratio in a multi-tubular methane steam and dry reformer by utilizing of CLC

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Journal of Energy Chemistry 2015年第1期24卷 54-64页

作者： Mohsen abbasi mehdi Farniaei Mohammad Reza Rahimpour Alireza Shariati Department of Chemical Engineering School of Chemical and Petroleum Engineering Persian Gulf UniversityBushehr 75169 Iran Department of Chemical Engineering Shiraz University of TechnologyShiraz 71555-313 Iran Department of Chemical Engineering School of Chemical and Petroleum Engineering Shiraz UniversityShiraz 71345 Iran

For syngas production, the combustion of fossil fuels produces large amounts of CO2 as a greenhouse gas annually which intensifies global warming. In this study, chemical looping combustion （CLC） has been utilized for the elimination of CO2 emission to atmosphere during simultaneous syngas production with different H2/CO ratio in steam reforming of methane （SR） and dry reforming of methane （DR） in a CLC-SR-DR configuration. In CLC-SR-DR with 184 reformer tubes （similar to an industrial scale steam reformer in Zagros Petrochemical Company, Assaluyeh, Iran）, DR reaction occurs over Rh-based catalysts in 31 tubes. Also, SR reaction is happened over Ni-based catalysts in 153 tubes. CLC via employment of Mn-based oxygen carriers supplies heat for DR and SR reactions and produces CO2 and H2O as raw materials simultaneously. A steady state heterogeneous catalytic reaction model is applied to analyze the performance and applicability of the proposed CLC-SR-DR configuration. Simulation results show that combustion efficiency reached 1 at the outlet of fuel reactor （FR）. Therefore, pure CO2 and H2O can be recycled to DR and SR sides, respectively. Also, CH4 conversion reached 0.2803 and 0.7275 at the outlet of SR and DR sides, respectively. Simulation results indicate that, 3223 kmol.h-l syngas with a H2/CO ratio equal to 9.826 was produced in SR side of CLC-SR-DR. After that, 1844 kmol.h-1 syngas with a H2/CO ratio equal to 0.986 was achieved in DR side of CLC-SR-DR. Results illustrate that by increasing the number of DR tubes to 50 tubes and considering 184 fixed total tubes in CLC-SR-DR, CH4 conversions in SR and DR sides decreased 2.69% and 3.31%, respectively. However, this subject caused total syngas production in SR and DR sides （in all of 184 tubes） enhance to 5427 kmol-h-1. Finally, thermal and molar behaviors of the proposed configuration demonstrate that CLC-SR-DR is applicable for simultaneous syngas production with high and low Hx/CO ratios in an environmental fr

关键词： chemical looping combustion (CLC) dry reforming of methane (DR) steam reforming of methane carbon dioxide capturing syngas produc-tion

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Investigation of parameters influencing erosive wear using DEM

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Friction 2020年第1期8卷 136-150页

作者： Akbar JAFARI Reza abbasi HATTANI Department of Mechanical Engineering Sirjan University of TechnologySirjan ***Iran

The effects of several parameters on the erosive wear were studied using the discrete element method(DEM).The Finnie model was implemented using an open‐source *** the time integration,the Gear algorithm was used,and to ensure the accuracy of the DEM results,a time‐step sensitivity analysis was *** problem was modeled in two parts:first,the impact of a single particle on a surface was modeled,and then a more general model was prepared to examine the wear of surfaces under the flow of *** effects of the surface area,impact angle,speed,particle size,particle density,Young’s modulus,Poisson’s ratio,and restitution coefficient on the wear were studied numerically,and the results are discussed herein.

关键词： wear erosion Finnie discrete element

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GA-based approach to phase compensation of large phased array antennas

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Journal of Systems Engineering and Electronics 2018年第4期29卷 723-730页

作者： ZAHEDI Amir abbasi ARAND Bijan Department of Electrical and Computer Engineering Tarbiat Modares University

The investigation of the effect of electrical and mechanical errors on the performance of a large active phased array antenna is studied. These errors can decrease the antenna performance, for instance, the gain reduction, side lobe level enhancement, and incorrect beam direction. In order to improve the performance of the antenna in the presence of these errors, phase error correction of large phased array antennas using the genetic algorithm（GA） is implemented. By using the phase compensation method, the antenna overall radiation pattern is recovered close to the ideal radiation pattern without error. By applying the simulation data to a 32×40 array of elements with a square grid at the frequency of S-band and measurement of the radiation pattern, the effectiveness of the proposed method is verified.

关键词： antenna genetic algorithm (GA) phased array radi-ating element.

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Microstructural Evolution of Nb–V–Mo and V Containing TRIP-assisted Steels during Thermomechanical Processing

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Journal of Materials Science & Technology 2017年第4期33卷 311-320页

作者： Erfan abbasi William Mark Rainforth Department of Materials Science and Engineering The University of Sheffield

The microstructural evolution and precipitation behaviour of Nb–V–Mo and single V containing transformation induced plasticity assisted steels were investigated during thermomechanical processing. A plane strain compression testing machine was used to simulate the thermomechanical processing. Microstructures were characterised by optical microscopy, scanning-transmission electron microscopy and microanalysis, and X-ray diffraction analysis, and Vickers hardness was obtained from the deformed specimens. The resulting microstructure of both Nb–V–Mo and V steels at room temperature primarily consisted of an acicular/bainitic ferrite, retained austenite and martensite surrounded by allotriomorphic *** TEM analysis showed that a significant number of Nb（V,Mo）（C,N） precipitates were formed in the microstructure down to the finishing stage in Nb–V–Mo steel（i.e. 830℃）. It was also found that the V（C,N）precipitation primarily occurred in both ferrite and deformed austenite below the finishing stage. The results suggested that Nb–Mo additions considerably increased the temperature stability of microalloy precipitates and controlled the microstructural evolution of austenite. However, the microalloy precipitation did not cause a significant precipitation strengthening in both Nb–V–Mo and V steels at room temperature.

关键词： Microalloyed TRiP-assisted steel Thermomechanical processing Precipitation behaviour Microstructural evolution

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A Study on Flame Forming of Bowl Shaped Surface with Various Spiral Irradiating Schemes

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Acta Mechanica Solida Sinica 2016年第3期29卷 328-336页

作者： mehdi Safari Department of Mechanical Engineering Arak University of Technology

In this paper, various strategies of spiral irradiating scheme for the flame forming of a bowl shaped surface are investigated experimentally and numerically. Experimental work is performed using a flame torch integrated with a 2-axis CNC workstation. The ABAQUS implicit solver is used in the numerical simulation. Three different strategies of the spiral irradiating scheme are investigated for the flame forming of a bowl shaped surface. The first strategy is the Simple spi- ral irradiating scheme, the second is the Rotational spiral irradiating scheme, and the third is the Symmetrical-Rotational spiral irradiating scheme. The results show that using the Symmetrical- Rotational spiral irradiating scheme, a bowl shaped surface with the maximum deformation can be produced, followed by using the Rotational scheme, and the Simple spiral scheme. It is also concluded from the results that the spiral irradiating scheme with Symmetrical-Rotational, Rota- tional and Simple spiral schemes lead to the maximum symmetries in the produced bowl shaped surface, respectively. All the numerical results are in good agreement with the experimental ob- servations.

关键词： flame forming bowl shaped surface spiral irradiating strategy

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A refined finite element method for bending analysis of laminated plates integrated with piezoelectric fiber-reinforced composite actuators

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Acta Mechanica Sinica 2018年第4期34卷 689-705页

作者： J.Rouzegar A.abbasi Department of Mechanical and Aerospace Engineering Shiraz University of Technology

This research presents a finite element formulation based on four-variable refined plate theory for bending analysis of cross-ply and angle-ply laminated composite plates integrated with a piezoelectric fiber-reinforced composite actuator under electromechanical loading. The four-variable refined plate theory is a simple and efficient higher-order shear deformation theory, which predicts parabolic variation of transverse shear stresses across the plate thickness and satisfies zero traction conditions on the plate free surfaces. The weak form of governing equations is derived using the principle of minimum potential energy, and a 4-node non-conforming rectangular plate element with 8 degrees of freedom per node is introduced for discretizing the domain. Several benchmark problems are solved by the developed MATLAB code and the obtained results are compared with those from exact and other numerical solutions, showing good agreement.

关键词： Finite elementmethod Laminated plate Piezoelectric fiber-reinforced composite(PFRC)actuator Piezoelectric Refined plate theory Smart structures

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BLUNT CRACK-TIP ELASTOPLASTIC ZONE OF MIXED MODE FRACTURE

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Acta Mechanica Solida Sinica 2014年第5期27卷 531-541页

作者： mehdi Khojastehpour Department of Biosystems Engineering Ferdowsi University of Mashhad

This article discusses the characterization of fracture process zone at the tip of a blunt crack in elastoplastic materials under mixed mode loading. The analysis includes the description of elastoplastic zone geometry around the blunt crack tip for predicting crack growth direction. The deformed zone appearing at the crack front is described by presenting a criterion based on the subloading surface concept falling within the framework of unconventional plasticity. The mixed mode crack propagates along the minimum value of the elastoplastic region. The present solutions are reduced to those previously reported in literature, when the elastic perfectly plastic material is considered.

关键词： crack fracture elastic plastic materials stress concentration

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Human reliability analysis in maintenance team of power transmission system protection

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Protection and Control of Modern Power Systems 2020年第1期5卷 290-302页

作者： mehdi Tavakoli mehdi Nafar Department of Electrical Engineering Marvdasht BranchIslamic Azad UniversityMarvdashtIran

The requirement for reliable electrical energy supply increases continuously because of its vital role in our ***,events due to various factors in the power grid can cause energy supply to be *** of these factors is human error and thus human reliability analysis is a serious element in the *** first step is to identify the roots of human error,on which there has been limited research in this *** this paper,the potential and actual causes of human error in maintenance teams of power transmission system protection are identified and predicted within a framework of human factors analysis and classification system ***,human error factors are ranked to help improve human *** proposed method is implemented in the Fars Electricity Maintenance Company.

关键词： Power transmission system protection Maintenance teams Human reliability HFACS method

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Alleviation of spike stall in axial compressors utilizing grooved casing treatment

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Chinese Journal of Aeronautics 2015年第3期28卷 649-658页

作者： Reza Taghavi-Zenouz Sarallah abbasi School of Mechanical Engineering Iran University of Science and Technology School of Mechanical Engineering Arak University of Technology

Abstract This article deals with application of grooved type casing treatment for suppression of spike stall in an isolated axial compressor rotor blade row. The continuous grooved casing treatment covering the whole compressor circumference is of 1.8 mm in depth and located between 90% and 108% chord of the blade tip as measured from leading edge. The method of investigation is based on time-accurate three-dimensional full annulus numerical simulations for cases with and without casing treatment. Discretization of the Navier Stokes equations has been carried out based on an upwind second-order scheme and k-a-SST （Shear Stress Transport） turbulence modeling has been used for estimation of eddy viscosity. Time-dependent flow structure results for the smooth casing reveal that there are two criteria for spike stall inception known as leading edge spillage and trailing edge backftow, which occur at specific mass flow rates in near-stall conditions. In this case, two dominant stall cells of different sizes could be observed. The larger one is caused by the spike stall covering roughly two blade passages in the circumferential direction and about 25% span in the radial direction. Spike stall disturbances are accompanied by lower frequencies and higher amplitudes of the pressure signals. Casing treatment causes flow blockages to reduce due to allevi- ation of backflow regions, which in turn reduces the total pressure loss and increases the axial veloc- ity in the blade tip gap region, as well as tip leakage flow fluctuation at higher frequencies and lower amplitudes. Eventually, it can be concluded that the casing treatment of the stepped tip gap type could increase the stall margin of the compressor. This fact is basically due to retarding the movement of the interface region between incoming and tip leakage flows towards the rotor leading edge Diane and suttressing the reversed flow around the blade trailing edee.

关键词： Axial compressor Casing treatment Frequency spectrum Spike stall inception Tip leakage flow

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Movement of Intransitive Permutation Groups Having Maximum Degree

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Chinese Annals of Mathematics,Series B 2012年第1期33卷 143-148页

作者： mehdi ALAEIYAN mehdi REZAEI School of Mathematics Iran University of Science and Technology

Let G be a permutation group positive integer. Then the movement of G on a set Ω with no fixed points in Ω, and m be a is defined as move（G）：=supГ{[Г^9 ／Г｜｜g ∈ G}. It F was shown by Praeger that if move（G） = m, then ｜Ω｜ ≤ 3m ＋ t - 1, where t is the number of G-orbits on ≤. In this paper, all intransitive permutation groups with degree 3m ＋ t - 1 which have maximum bound are classified. Indeed, a positive answer to her question that whether the upper bound ｜Ω｜ = 3m ＋ t - 1 for ｜Ω｜ is sharp for every t 〉 1 is given.

关键词： Intransitive permutation groups Bounded movement Orbit

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