排序方式： 共有176条查询结果，搜索用时 15 毫秒
81.
Behrouz Kheirfam 《Annals of Operations Research》2013,211(1):209-224
We present a full Nesterov and Todd step primal-dual infeasible interior-point algorithm for symmetric optimization based on Darvay’s technique by using Euclidean Jordan algebras. The search directions are obtained by an equivalent algebraic transformation of the centering equation. The algorithm decreases the duality gap and the feasibility residuals at the same rate. During this algorithm we construct strictly feasible iterates for a sequence of perturbations of the given problem and its dual problem. Each main iteration of the algorithm consists of a feasibility step and some centering steps. The starting point in the first iteration of the algorithm depends on a positive number ξ and it is strictly feasible for a perturbed pair. The feasibility steps find strictly feasible iterates for the next perturbed pair. By using centering steps for the new perturbed pair, we obtain strictly feasible iterates close to the central path of the new perturbed pair. The algorithm finds an ?-optimal solution or detects infeasibility of the given problem. Moreover, we derive the currently best known iteration bound for infeasible interior-point methods. 相似文献
82.
In this paper we introduce a two phase version of the well-known Quadrature Domain theory, which is a generalized (sub)mean
value property for (sub)harmonic functions. In concrete terms, and after reformulation into its PDE version the problem boils
down to finding solution to
|
$ - \Delta u = (\mu_+ - \lambda_+ )\chi_{\{u > 0\}} - (\mu_- - \lambda_- )\chi_{\{u < 0\}} ~~~{\rm in }~~~ {I\!\!R}^N. $ - \Delta u = (\mu_+ - \lambda_+ )\chi_{\{u > 0\}} - (\mu_- - \lambda_- )\chi_{\{u < 0\}} ~~~{\rm in }~~~ {I\!\!R}^N. 相似文献
83.
84.
Behrouz Kheirfam 《Numerical Algorithms》2012,59(4):589-606
Interior-point methods for semidefinite optimization problems have been studied frequently, due to their polynomial complexity and practical implications. In this paper we propose a primal-dual infeasible interior-point algorithm that uses full Nesterov-Todd (NT) steps with a different feasibility step. We obtain the currently best known iteration bound for semidefinite optimization problems. 相似文献
85.
Farbod Salahi Mohammad Javad Taghizadeh Hamid Arvinnezhad Mehdi Moemeni Khosrow Jadidi Behrouz Notash 《Tetrahedron letters》2014
The catalytic, highly regio-, diastereo-, and enantioselective synthesis of a small library of chiral spirooxindolopyrrolizidines via a three-component 1,3-dipolar cycloaddition reaction of azomethine ylides, derived from isatin, with electron-deficient dipolarophiles, 3-(2-alkenoyl)-1,3-oxazolidin-2-ones, is described. A chiral copper(II) complex of cyclohexane-1,2-bis(arylmethyleneamine) catalyzed this process at room temperature. The reaction mechanism is discussed on the basis of the assignment of the absolute configuration of the cycloadducts. 相似文献
86.
The self-assembly of a new flexible tritopic pyrazine-pyridine ligand (pz-3-py) with HgX(2) (X = Cl, Br) was investigated. The results show that coordinated chloride and bromide anions play different roles, and two architecturally different coordination polymers were obtained with the anions used. Where X = Cl, in [Hg(μ(3)-pz-3-py)Cl(2)](n) (1), the 2D network is isolated, while for X = Br, in [Hg(μ-pz-3-py)Br(2)](n) (2), a 1D zigzag chain is constructed. Our results show that noncovalent interactions such as hydrogen bond, halogen···halogen, and halogen···π interactions, when acting cooperatively, are driving forces for the selection of different structures. 相似文献
87.
Mohammad Navid Soltani Rad Zeinab Asrari Somayeh Behrouz Gholam Hossein Hakimelahi Ali Khalafi‐Nezhad 《Helvetica chimica acta》2011,94(12):2194-2206
The ‘click synthesis’ of some oxiconazole analogs 5a – 5v having 1H‐1,2,3‐triazolyl residues by Huisgen cycloaddition was achieved in four steps (Scheme 1). Oximation of phenacyl chloride ( 1 ) followed by azidation of 2‐chloro‐1‐phenylethanone oxime ( 2 ) provided azido ketoxime 3 . The CuI‐catalyzed Huisgen cycloaddition of 3 with terminal alkynes gave the 4‐substituted (at the triazole) 2‐(1H‐1,2,3‐triazol‐1‐yl)‐1‐phenylethanone oximes 4a – 4i . The O‐alkylation of 4a – 4i with various alkyl halides resulted in the formation of the target molecules 5a – 5v in good yields. 相似文献
88.
Calix[4]arene derivatives containing ferrocene units at the upper rim have been synthesized and their anion‐binding and sensing investigated towards anions such as chloride, bromide and hydrogen sulfate by cyclic voltammetry. Electrochemical studies show that these redox‐active ligands electrochemically recognize chloride and bromide anions. These compounds have excellent selectivity for chloride and bromide ions, in the comparison with hydrogen sulfate anion. With ferrocenyl Schiff base calix[4]arene 1 an anodic shift as large as 302 mV is observed on addition of four equivalents of Cl− anion. Also electrochemical and UV–vis spectroscopic titrations ferrocenyl calix[4]arene derivatives 1 with chloride and bromide ions and 2 (only with Cl−) indicate a 1:1 binding‐stiochiometry. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
89.
Mohammad Navid Soltani Rad Ali Khalafi‐Nezhad Somayeh Behrouz 《Helvetica chimica acta》2009,92(9):1760-1774
The syntheses of some novel carboacyclic nucleosides, 17a – 17o , containing oxiconazole‐like scaffolds, are described (Schemes 1–3). In this series of carboacyclic nucleosides, pyrimidine as well as purine and other imidazole derivatives were employed as an imidazole successor in oxiconazole. These compounds could be prepared in good yields by using two different strategies (Schemes 1 and 2). Due to Scheme 1, the N‐coupling of nucleobases with 2‐bromoacetophenones was attained for 18a – 18e , and their subsequent oximation affording 19a – 19e and finally O‐alkylation with diverse alkylating sources resulted in the products 17a – 17g, 17n , and 17o . In Scheme 2, use of 2‐bromoacetophenone oximes 20 , followed by N‐coupling of nucleobases, provided 19f – 19j whose final O‐alkylation produced 17h – 17m (Scheme 2). For the rational interpretation of the dominant formation of (E)‐oxime ethers rather than (Z)‐oxime isomers, PM3 semiempirical quantum‐mechanic calculations were discussed and the calculations indicated a lower heat of formation for (E)‐isomers. 相似文献
90.
Behrouz Shaabani Dr. Babak Mirtamizdoust Muhammad Shadman Hoong‐Kun Fun 《无机化学与普通化学杂志》2009,635(15):2642-2647
A novel 1D PbII coordination polymer containing Pb2‐(μ‐N3)2 unit [Pb(dmp)(N3)2]n (dmp = 2,9‐dimethyl‐1,10‐phenanthroline) has been prepared and characterized. Single‐crystal X‐ray diffraction analyses show that the coordination number for PbII ions is six, PbN6, with “stereochemically active” electron lone pairs and the coordination sphere being hemidirected. The single‐crystal X‐ray data show the chains interact with each other through the π–π stacking interactions, which create a 3D framework. The structure of title complex has been optimized by density functional theory. Structural parameters and IR spectra for the complex are in agreement with the crystal structure. 相似文献
|