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Modeling multi regional counter flow combustion of lycopodium dust cloud with considering radiative heat loss

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Journal of Central South University 2017年第11期24卷 2638-2648页

作者： Bidabadi Mehdi ebrahimi Farzaneh Bordbar Vahid School of Mechanical Engineering Department of Energy ConversionCombustion Research LaboratoryIran University of Science and Technology(IUST)Tehran ***Iran

In this work, an analytical model is presented to simulate the combustion process of organic dust with considering radiative heat loss effect in counterflow configuration. A thermal model has been generated to estimate the flame propagation speed in various dust concentrations. The structure of premixed flame in a symmetric configuration, containing uniformly distributed volatile fuel particles, with nonunity Lewis number is examined with strain rate issue. The flame structure is divided into six zones: first heating, drying, second heating, volatile evaporation, reaction and post-flame zones. At first, the governing equations of lycopodium combustion dust particles are written for each zone. Finally, boundary conditions and matching conditions are applied for each zone in order to solve the differential equations. The purpose of this article is to analyze radiation heat transfer on lycopodium flame propagation dust particles and characteristics to check the effect of parameters on combustion.

关键词： radiative heat counterflow lycopodium analytical model

Finite element analysis of stress and strain distributions in mortise and loose tenon furniture joints

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Journal of Forestry research 2014年第3期25卷 677-681页

作者： Mohammad Derikvand ghanbar ebrahimi Department of Wood and Paper Science and Technology College of Agriculture and Natural Resources University of Tehran

We studied the effect of loose tenon dimensions on stress and strain distributions in T-shaped mortise and loose tenon （M＆amp;LT） furni-ture joints under uniaxial bending loads, and determined the effects of loose tenon length （30, 45, 60, and 90 mm） and loose tenon thickness （6 and 8 mm） on bending moment capacity of M＆amp;LT joints constructed with polyvinyl acetate （PVAc） adhesive. Stress and strain distributions in joint elements were then estimated for each joint using ANSYS finite element （FE） software. The bending moment capacity of joints increased significantly with thickness and length of the tenon. Based on the FE analysis results, under uniaxial bending, the highest shear stress values were obtained in the middle parts of the tenon, while the highest shear elastic strain values were estimated in glue lines between the tenon sur-faces and walls of the mortise. Shear stress and shear elastic strain values in joint elements generally increased with tenon dimensions and corre-sponding bending moment capacities. There was consistency between predicted maximum shear stress values and failure modes of the joints.

关键词： bending moment capacity, failure mode, finite element,furniture, mortise and loose tenon joint stress and strain distributions

Evolutionary algorithm for optimization of multilayer coatings

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Chinese Physics B 2018年第10期27卷 531-536页

作者： Mahdi ebrahimi Mohsen ghasemi Zeinab Sajjadi Department of Physics Payame Noor University Department of Physics Faculty of SciencesShahrekord University Department of Computer & Mathematics Sheikhbahaee University

In this paper, a new evolutionary algorithm, the well-known imperialist competition algorithm, is proposed for optimizing the optical thin-films. In this method, the process is modeled of the competition between countries as imperialists and their colonizing of others as colonies. This algorithm could be an appropriate alternative to some of the more popular algorithms for optimizing the optical thin-films for good performance. The polarizer and edge filter for example are designed by using the imperialist competition algorithm method and the results are compared with those from two optimization high-performance methods： the genetic algorithm and differential evolutionary algorithm. Based on these results,the performance of the imperialist competition algorithm method shows that this algorithm is not sensitive to the change of its parameters and it can be an important advantage for quickly achieving a global optimal point. On the other hand the results show a better ratio of P-polarization transmittance to S-polarization transmittance in the design of a 1540-nm polarizer, which is more appropriate than the results from the other two methods. In the second design, an edge filter with a lower number of layers and more uniform bandpass spectrum than the counterparts of those methods is obtained. These results indicate that the imperialist competition algorithm is a robust method for optical thin-film designs.

关键词： multilayers optimization thin-film imperialist competition algorithm

One-pot synthesis of 1,3-thiazolidin-4-one using Bi(SCH_2COOH)_3 as catalyst

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Chinese Chemical Letters 2013年第5期24卷 389-391页

作者： Naser Foroughifar Sattar ebrahimi Faculty of Chemistry North Tehran BranchIslamic Azad University Department of Chemistry Malayer Branch Islamic Azad University

A catalytic multi-component reaction involving aromatic amine,aromatic aldehydes,mercapto acid as substrates and Bi（SCH_2COOH）_3 as catalyst under solvent free conditions,afforded thiazolidin-4-one in good *** efficiency of the catalyst was proved with a variety of substrates,ranging from electrondeficient to electron-rich aldehydes.

关键词： Thiazolidin-4-one Mercapto acid Multicomponent Thioglycolic acid

Strength performance of mortise and loose-tenon furniture joints under uniaxial bending moment

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Journal of Forestry research 2014年第2期25卷 483-486页

作者： Mohammad Derikvand ghanbar ebrahimi Department of Wood and Paper Science and Technology College of Natural ResourcesUniversity of Tehran

We determined the effects of adhesive type and loose tenon dimensions （length and thickness） on bending strength of T-shaped mor- tise and loose-tenon joints. Polyvinyl acetate （PVAc） and two-component polyurethane （PU） adhesives were used to construct joint specimens. The bending moment capacity of joints increased significantly with increased length and thickness of the loose tenon. Bending moment capacity of joints constructed with PU adhesive was approximately 13% higher than for joints constructed with PVAc adhesive. We developed a predictive equation as a function of adhesive type and loose tenon dimensions to estimate the strength of the joints constructed of oriental beech （Fagus orientalis L.） under uniaxial bending load.

关键词： bending moment capacity mortise and loose tenon loose tenon dimensions polyvinyl acetate two-component polyurethane

The combinatorics of green＇s functions in planar field theories

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Frontiers of physics 2016年第6期11卷 1-23页

作者： Kurusch ebrahimi-Fard Frederic Patras ICMAT C/Nicolds Cabrera no. 13-15 28049 Madrid Spain. On leave from UHA Mulhouse France Univ. de Nice Labo. J-A. Dieudonnd UMR 7351 CNRS Parc Valrose 06108 Nice Cedex 02 France

The aim of this exposition is to provide a detailed description of the use of combinatorial algebra in quantum field theory in the planar setting. Particular emphasis is placed on the relations between different types of planar green’s functions. The primary object is a Hopf algebra that is naturally defined on variables representing non-commuting sources, and whose coproduct splits into two half-coproducts. The latter give rise to the notion of an unshuffle bialgebra. This setting allows a description of the relation between full and connected planar green’s functions to be given by solving a simple linear fixed point equation. We also include a brief outline of the consequences of our approach in the framework of ordinary quantum field theory.

关键词： planar field theory green’s functions free probability Hopf algebra shuffle algebra partitions

Lattice parameters of Ti–4Al–2V alloy with thermal oxidation

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rare Metals 2016年第2期35卷 149-153页

作者： Faraz Omidbakhsh Ali reza ebrahimi Department of Mechanical Engineering Tabriz Branch Islamic Azad University Mining and Metallurgical Engineering Department Amirkabir University of Technology

In this study, the effect of thermal oxidation on the lattice parameters of Ti-4Al-2V alloy was *** were oxidized at 450, 600 and 650 °C for 1-7 h in electric furnace under air atmosphere. The lattice parameters were determined using the Cohen method as a function of oxidation time at each temperature. The lattice parameters of as-received alloy are calculated as a = 0.29289 nm and c = 0.46652 nm. The thermal oxidation at 450 °C results in a gradual increase in a-parameter, whereas it goes through a maximum at higher temperatures（600 and 700 °C）. The results show that these maximums are reduced to an approximately constant value after a long-time oxidation. The c-parameter generally increases over the whole treatment condition. It is believed that these variations could be due to the dissolution of oxygen atoms in octahedral sites of hcp lattice of titanium.

关键词： Lattice parameter Ti-4Al-2V X-ray diffraction Cohen method Octahedral sites

Effect of ultrasonic irradiation on particle size,reagents consumption,and feed ash content in coal flotation

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International Journal of Coal Science & Technology 2020年第4期7卷 787-795页

作者： Hossein ebrahimi Mohammad Karamoozian Department of Mining Petroleum and GeophysicsShahrood University of TechnologyShahroodIran

Ultrasonic waves have a lot of use in the particle surface *** flotation is one of the methods associated with surface properties,this paper investigates the effect of these waves on performance,particle size,reagents,and feed ash content in coal *** accomplish this goal,coal samples in three size fractions,including coarse(-800 to+400μm),medium(-400 to+100 μm)and fine(-100μm)with various feed ash *** flotation experiments were evaluated by process indexes such as yield,combustible recovery,and selectivity *** results indicated the increasing of *** increasing was significant in medium ***,the results showed that in presence of ultrasonic waves,the collector and frother consumption *** also,applying ultrasonic waves would result more combustible recovery and selectivity *** ash selectivity index had the highest impact for high feed ash content.

关键词： Flotation Ultrasonic waves Coal Particle size reagents Feed ash

Projective Hilbert modules and sequential approximations

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Science China Mathematics 2025年第1期 137-168页

作者： Lawrence g.Brown Huaxin Lin Department of Mathematics Purdue University Department of Mathematics East China Normal University Department of Mathematics University of Oregon Shanghai Institute for Mathematics and Interdisciplinary Sciences

We show that when A is a separable C*-algebra,every countably generated Hilbert A-module is projective（with bounded module maps as morphisms）.We also study the approximate extensions of bounded module *** the case where A is a σ-unital simple C*-algebra with strict comparison,and every strictly positive lower semicontinuous affine function on quasitraces can be realized as the rank of an element in the Cuntz semigroup,we show that the Cuntz semigroup is equivalent to unitarily equivalent classes of countably generated Hilbert A-modules if and only if A has stable rank one.

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