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81.
Hossein Mahdavi B. O. Mahdi Sadeghzadeh Nader Taheri Qazvini 《Journal of Polymer Science.Polymer Physics》2009,47(5):455-462
The phase behavior of poly(N‐tertbutylacrylamide‐co‐acrylamide) (PNTBAM) in pure water and mixture of water–methanol is studied at different temperatures. The different compositions of PNTBAM are prepared by free‐radical polymerization technique and their phase behavior is studied by turbidimetry. The effects of copolymer and solvent composition on the phase behavior of the copolymers are discussed. It has been suggested that the inhomogenities in polymer chains are responsible for lowering the rate of phase transition by increasing the N‐tertbutylacrylamide (NTBAM) and methanol contents in copolymer and mixture, respectively. For the first time we have revealed that there are second‐order binary interactions in the water–methanol which are dominant in the special range of copolymer composition. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 455–462, 2009 相似文献
82.
Mahdi Zarghami Ferenc Szidarovszky Reza Ardakanian 《Fuzzy Optimization and Decision Making》2008,7(1):1-15
All realistic Multi-Criteria Decision Making (MCDM) problems face various kinds of uncertainty. Since the evaluations of alternatives
with respect to the criteria are uncertain they will be assumed to have stochastic nature. To obtain the uncertain optimism
degree of the decision maker fuzzy linguistic quantifiers will be used. Then a new approach for fuzzy-stochastic modeling
of MCDM problems will be introduced by merging the stochastic and fuzzy approaches into the OWA operator. The results of the
new approach, entitled FSOWA, give the expected value and the variance of the combined goodness measure for each alternative.
Robust decision depends on the combined goodness measures of alternatives and also on the variations of these measures under
uncertainty. In order to combine these two characteristics a composite goodness measure will be defined. The theoretical results
will be illustrated in a watershed management problem. By using this measure will give more sensitive decisions to the stakeholders
whose optimism degrees are different than that of the decision maker. FSOWA can be used for robust decision making on the
competitive alternatives under uncertainty. 相似文献
83.
We propose an exact branch-and-bound algorithm for the problem of maximizing the minimum machine completion time on identical
parallel machines. The proposed algorithm is based on tight lower and upper bounds as well as an effective symmetry-breaking
branching strategy. Computational results performed on a large set of randomly generated instances attest to the efficacy
of the proposed algorithm.
相似文献
84.
In this paper, an experimental study and modeling by artificial neural networks were carried out to predict the generated microdroplet dimensionless size in a microfluidic system in order to formulate a water-in-oil emulsion. The various parameters that affect the size of microdroplets (flow rates, viscosities, surface tensions of both the two phases and the diameter of the microchannel) are studied and further grouped into dimensionless numbers; we used these numbers as input to the neural network and the dimensionless length as output. The better neural network architecture has 10 neurons in the hidden layer with a mean square error of 1.4 10?6 and a determination’s coefficient near 1 value. The relative importance of inputs on the size of the microdroplets has been determined using the Garson algorithm and the results are in good agreement with other works. 相似文献
85.
Mohammad Mahdi Najafpour Mojtaba Amini Mojtaba Bagherzadeh Davar M. Boghaei Vickie McKee 《Transition Metal Chemistry》2010,35(3):297-303
A manganese(II) complex of 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) has been synthesized and characterized by single-crystal
X-ray diffraction, elemental analyses, IR, and UV–Vis spectroscopic techniques. Oxidation of alcohols to their corresponding
aldehydes and ketones was conducted by this catalyst using oxone (2KHSO5·KHSO4·K2SO4) as an oxidant under biphasic reaction conditions (CH2Cl2/H2O) and tetra-n-butylammonium bromide as phase transfer agent under air at room temperature. Easy preparation, mild reaction conditions,
high yields of the products, short reaction times, no further oxidation to the corresponding carboxylic acids, high selectivity
and inexpensive reagents make this catalytic system a useful oxidation method for aliphatic and benzylic alcohols. 相似文献
86.
Haghighi MG Rashidi M Nabavizadeh SM Jamali S Puddephatt RJ 《Dalton transactions (Cambridge, England : 2003)》2010,39(47):11396-11402
The cyclometalated complexes [Pt(ppy)R(SMe(2))] or [Pt(bhq)R(SMe(2))], where ppyH = 2-phenylpyridine, bhqH = benzo[h]quinoline and R = methyl or p-tolyl, react with bis(diphenylphosphino)ethane, dppe, in a 1:1 ratio to give the corresponding complexes [Pt(κ(1)-C-ppy)R(dppe)] or [Pt(κ(1)-C-bhq)R(dppe)], in which the ppy or bhq ligands are monodentate and dppe is chelating. The similar reaction in a 2:1 ratio gives the binuclear complexes [{Pt(ppy)R}(2)(μ-dppe)] or [{Pt(bhq)R}(2)(μ-dppe)], in which the dppe ligands are in the unusual bridging bidentate bonding mode. 相似文献
87.
Two new coumarin-hemiterpene ether glucosides, 4'-O-(beta-D-glucopyranosyl) desoxylacarol (1), and 5-O-(beta-D-glucopyranosyl) lacarol (2), were isolated from the methanolic extract of the aerial parts of Artemisia armeniaca Lam. Their structures were established by means of spectroscopic analysis including 1H- and 2D-NMR, HRESIMS, and acid hydrolysis. In addition, a structurally related phenylpropanoic acid derivative (3) was obtained in small amounts, and its structure tentatively assigned as 3-(4-hydroxy-3-methylbutoxy)-4-methoxy melilotic acid. 相似文献
88.
Strong, surprising, and multifaceted effects of the width of the external surface layer Δ(ξ) and internal stresses on surface-induced pretransformation and phase transformations (PTs) are revealed. Using our further developed phase-field approach, we found that above some critical Δ(ξ)(*), a morphological transition from fully transformed layer to lack of surface pretransformation occurs for any transformation strain ε(t). It corresponds to a sharp transition to the universal (independent of ε(t)), strongly increasing the master relationship of the critical thermodynamic driving force for PT X(c) on Δ(ξ). For large ε(t), with increasing Δ(ξ), X(c) unexpectedly decreases, oscillates, and then becomes independent of ε(t). Oscillations are caused by morphological transitions of fully transformed surface nanostructure. A similar approach can be developed for internal surfaces (grain boundaries) and for various types of PTs and chemical reactions. 相似文献
89.
We present two linearization-based algorithms for mixed-integer nonlinear programs (MINLPs) having a convex continuous relaxation. The key feature of these algorithms is that, in contrast to most existing linearization-based algorithms for convex MINLPs, they do not require the continuous relaxation to be defined by convex nonlinear functions. For example, these algorithms can solve to global optimality MINLPs with constraints defined by quasiconvex functions. The first algorithm is a slightly modified version of the LP/NLP-based branch-and-bouund \((\text{ LP/NLP-BB })\) algorithm of Quesada and Grossmann, and is closely related to an algorithm recently proposed by Bonami et al. (Math Program 119:331–352, 2009). The second algorithm is a hybrid between this algorithm and nonlinear programming based branch-and-bound. Computational experiments indicate that the modified LP/NLP-BB method has comparable performance to LP/NLP-BB on instances defined by convex functions. Thus, this algorithm has the potential to solve a wider class of MINLP instances without sacrificing performance. 相似文献
90.
This paper proposes a new mathematical model to solve the cell formation, operator assignment and inter-cell layout problems, simultaneously. The objectives of proposed model are minimization of inter–intra cell part trips, machine relocation cost and operator related issues. Since the objective function of the proposed model consists of none commensurable statements, the preferred solution is obtained by the LP-metric approach. In order to validate the proposed model, some numerical examples are generated randomly and solved by branch and bound technique. Moreover; a real case study is illustrated in order to verify its applicability in an automobile producer company. Moreover the sensitivity analysis of proposed model shows that considering the operator assignment problem has significant impact on the overall system efficiency. 相似文献