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101.
In this paper the convergence of the RVM for a complex flow is studied, in function of three discretization parameters. Two of these parameters are related to the spatial discretization of the vorticity Γ (sheet or blob strength) and h (sheet length or core radius) and the third one to the time discretization Δt. Two main events are observed: first, the computation works but the convergence is not attained, secondly the computation fails. The first behaviour is attributed to a lack of accuracy and the second to a lack of numerical stability. Once the stability conditions are satisfied, decreasing the value of parameters always leads to convergence. To cite this article: I. Mortazavi et al., C. R. Mecanique 330 (2002) 409–416. 相似文献
102.
Vortical structure identification has more recently been applied in the study of the transport of vortical structures in low Reynolds number three-dimensional complex geometry flows. An important issue in this identification procedure is to choose an appropriate cut-off value which takes into consideration the finite precision vortex interfaces. This cut-off choice is studied in this Note and applied to an external flow around a curved cylinder. The vortex identification technique at different cut-off values is compared to the threshold of the vorticity field showing the efficiency of choosing the optimal tolerance gap. The computations are performed with a fully three-dimensional spectral/hp element method. To cite this article: A. Miliou et al., C. R. Mecanique 333 (2005). 相似文献
103.
Beheshteh Asadi Amir Landarani-Isfahani Iraj Mohammadpoor-Baltork Shahram Tangestaninejad Majid Moghadam Valiollah Mirkhani Hadi Amiri Rudbari 《Tetrahedron letters》2017,58(1):71-74
Fe3O4-TDSN-Bi(III) was utilized as an efficient and reusable catalyst for the regioselective one-pot synthesis of quinoline derivatives from arylamines, arylaldehydes and methyl propiolate under microwave irradiation and solvent-free conditions. Also, bis-quinolines were obtained in high yields from dialdehydes or diamines. Atom-economy, high to excellent yields, easy work-up, as well as simple catalyst recovery and reusability are the key features of this procedure. 相似文献
104.
Sulfonated palladium(II) N‐heterocyclic carbene complex immobilized on nano–micro size poly(4‐vinylpyridinium chloride) for Suzuki‐Miyaura cross‐coupling reaction
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Zari Pahlevanneshan Majid Moghadam Valiollah Mirkhani Shahram Tangestaninejad Iraj Mohammadpoor‐Baltork Saghar Rezaei 《应用有机金属化学》2015,29(10):678-682
The sulfonated palladium(II) N‐heterocyclic carbene complex PdII(NHC)SO3?, supported on poly(4‐vinylpyridinium chloride), was used as a heterogeneous, recyclable and active catalyst for the Suzuki–Miyaura reaction. This catalyst was applied for coupling of various aryl halides with phenylboronic acid and the corresponding products were obtained in excellent yields and short reaction times. The catalyst was characterized using Fourier transform infrared and diffuse reflectance UV–visible spectroscopies, scanning electron microscopy and elemental analysis. After each reaction, the catalyst was recovered easily by simple filtration and reused several times without significant loss of its catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
105.
Immobilization of palladium(II)‐containing bis(imidazolium) ligand on ion‐exchange resins: efficient and reusable catalysts for CC coupling reactions
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Zari Pahlevanneshan Majid Moghadam Valiollah Mirkhani Shahram Tangestaninejad Iraj Mohammadpoor‐Baltork Ahmad R. Khosropour 《应用有机金属化学》2015,29(6):346-352
Suzuki reactions catalysed by a palladium(II) complex of a functionalized bis(imidazolium) ligand, PdII(BIM), immobilized on Dowex 50 WX8 and Amberlite IR‐120 ion‐exchange resins as heterogeneous, recyclable and active catalysts are reported. The catalysts, PdII(BIM)@Amberlite IR‐120 and PdII(BIM)@Dowex 50 WX8, were characterized using Fourier transform infrared and diffuse‐reflectance UV–visible spectroscopies and scanning electron microscopy. These heterogeneous catalysts are oxygen‐insensitive and air‐ and moisture‐stable in C? C coupling reactions, and are reusable several times without significant loss of their catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
106.
Farhad Shirini Gholam Hossein Imanzadeh Seyyed Ali Reza Mousazadeh Iraj Mohammadpoor-Baltork Masoumeh Abedin 《中国化学快报》2010,21(10):1187-1190
<正>A mild and efficient method for the conversion of alcohols to their corresponding methoxymethyl ethers and acetates using benzyltriphenylphosphonium tribromide(BTPTB) as catalyst is described.All reactions were performed under completely heterogeneous reaction conditions in good to high yields. 相似文献
107.
Farzin Taghipourian Iraj Mahdavi Nezam Mahdavi-Amiri Ahmad Makui 《Applied Mathematical Modelling》2012
Hub location problem has been used in transportation network to exploit economies of scale. For example, a controversial issue in the planning of air transportation networks is inclement weather or emergency conditions. In this situation, hub facilities would not be able to provide a good service to their spoke nodes temporarily. Thus, some other kinds of predetermined underutilized facilities in the network are used as virtual hubs to host some or all connections of original hubs to recover the incurred incapacitation and increase network flexibility and demand flow. In such an unexpected situation, it is not unreasonable to expect that some information be imprecise or vague. To deal with this issue, fuzzy concept is used to pose a more realistic problem. Here, we present a fuzzy integer liner programming approach to propose a dynamic virtual hub location problem with the aim of minimizing transportation cost in the network. We examine the effectiveness of our model using the well-known CAB data set. 相似文献
108.
S Safaei I Mohammadpoor-Baltork AR Khosropour M Moghadam S Tangestaninejad V Mirkhani 《Molecular diversity》2012,16(3):591-600
A variety of pyrazolo[3,4-d]pyrimidine-6(7H)-thione derivatives were easily synthesized with a novel, simple, efficient, and regioselective method via three-component condensation reaction of 5-methyl-1H-pyrazol-3-amine, arylisothiocyanates, and aldehydes in the presence of catalytic amount of p-toluenesulfonic acid (p-TSA) in 1-butyl-3-methylimidazolium bromide ionic liquid with excellent yields and short reaction times. 相似文献
109.
Elham Safaei Iraj SaberikiaAndrzej Wojtczak Zvonko Jagli?i?Anna Kozakiewicz 《Polyhedron》2011,30(6):1143-1148
Two aminoethanol derivatives of aminophenol ligands were synthesized and characterized by IR and 1H NMR spectroscopies. The binuclear iron(III) complexes of these ligands have been prepared and characterized by IR, 1H NMR and UV-Vis spectroscopic techniques, cyclic voltammetry, single crystal X-ray diffraction and magnetic susceptibility studies. X-ray analysis revealed binuclear complexes, Fe2(L2), in which Fe(III) centers are surrounded by two phenolate and hydroxyl oxygen atoms, and amine nitrogens of the ligands. The metal active sites of both complexes are held together by the two above mentioned hydroxyl bridges. Variable temperature magnetic susceptibility indicates antiferromagnetic coupling between the iron centers of both complexes. This exchange coupling is stronger for Fe2(Lae)2, such that it shows a room temperature strong coupling between the two iron centers. The investigated complexes undergo irreversible electrochemical oxidation and reduction. 相似文献
110.
Oxygenation of sulfides catalysed by SBA‐15‐immobilized molybdenum(VI) complex of a bis(phenol) diamine ligand using aqueous hydrogen peroxide as a green oxidant
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A highly efficient and reusable molybdenum‐based catalyst has been synthesized by covalent grafting of a bis(phenol) diamine ligand, namely 2‐(((2‐bromoethyl)(2‐((3,5‐di‐tert‐butyl‐2‐hydroxybenzyl)amino)ethyl)amino)methyl)‐4,6‐di‐tert‐butylphenol, onto functionalized ordered mesoporous silica (SBA‐15) followed by complexation with MoO2(acac)2. The resulting organic–inorganic hybrid material was found to be a highly effective catalyst for oxygenation of various sulfides to their corresponding sulfoxides or sulfones. The catalyst was characterized using transmission and scanning electron microscopies, X‐ray photoelectron, Fourier transform infrared and atomic absorption spectroscopies, Brunauer–Emmett–Teller surface area analysis and thermogravimetric analysis. Mild reaction conditions, high selectivity and easy recovery and reusability of the catalyst render the presented protocol very useful for addressing industrial needs and environmental concerns. 相似文献