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31.
We present a self-adaptive and distributed metaheuristic called Coalition-Based Metaheuristic (CBM). This method is based
on the Agent Metaheuristic Framework (AMF) and hyper-heuristic approach. In CBM, several agents, grouped in a coalition, concurrently
explore the search space of a given problem instance. Each agent modifies a solution with a set of operators. The selection
of these operators is determined by heuristic rules dynamically adapted by individual and collective learning mechanisms.
The intention of this study is to exploit AMF and hyper-heuristic approaches to conceive an efficient, flexible and modular
metaheuristic. AMF provides a generic model of metaheuristic that encourages modularity, and hyper-heuristic approach gives
some guidelines to design flexible search methods. The performance of CBM is assessed by computational experiments on the
vehicle routing problem. 相似文献
32.
Caruso A Voisin-Chiret AS Lancelot JC Sinicropi MS Garofalo A Rault S 《Molecules (Basel, Switzerland)》2008,13(6):1312-1320
A synthetic method for the preparation of 6-aryl-1,4-dimethyl-9H-carbazoles involving a palladium catalyzed coupling reaction of 1,4-dimethyl-9H-carbazole-6-boronic acids and (hetero)aryl halides is described. 相似文献
33.
Nguyen TM Sanchez-Salvatori Mdel R Wypych JC Marazano C 《The Journal of organic chemistry》2007,72(15):5916-5919
The reaction of Zincke salts with primary amines to give pyridinium salts generally requires rather elevated temperature to go to completion (50-100 degrees C). It is shown that the addition of 1 equiv of a secondary amine allows formation, at ambient temperature, of intermediate aminopentadiene imine salts which can be isolated and were found to cyclize in acidic medium to give pyridinium salts at temperatures which do not exceed 50 degrees C. If this process has a tendency to give lower yields of pyridinium salt than the standard Zincke procedure, it can be advantageous in some cases, as illustrated by the synthesis of pyridinium salts from amino acids, a challenging reaction which does not work starting from Zincke salt in the absence of diethylamine. More generally, the reaction can be extended to primary amines featuring polar functions, as exemplified by a pyridinium salt synthesis (75 degrees C) in 55% yield from l-carnosine. 相似文献
34.
Julien Blanckaert Véronique Bounor-Legaré Jannick Duchet-Rumeau Jean-Charles Majesté René Fulchiron 《Journal of Sol-Gel Science and Technology》2012,63(1):85-94
Polypropylene/silica microcomposites with high aspect ratio silica fillers were in situ generated into a molten polypropylene (PP) matrix. The synthesis of the inorganic domains are based on hydrolysis-condensation reactions of both alkoxysilanes precursors, the tetraethoxysilane (TEOS) and the Dynasil? 40 (composed of TEOS and partially condensed TEOS with residual ethoxy groups) respectively. The sol?Cgel reactions kinetics studied at room temperature into an acid hydroalcoholic medium for several conditions of pH associated to the processing conditions were the keys factors to control the deformability of the inorganic droplets. Thanks to a shearing hot stage coupled with an optical microscope, silica needles were obtained with a Dynasil? 40 solution treated 120?min at pH?=?3 in presence of 4?g of ethanol and then placed between two slices of PP in the stage. The deformation of the droplets were then observed once the material was molten and a shearing applied. On the contrary, no deformation was possible with TEOS precursors solutions. The results transposed to the microextruder process equipped at the die with a drawing line allowed to obtain a well pronounced elongated shape of the silica particles dispersed in the polypropylene matrix. 相似文献
35.
This paper presents an experimental study of flow development and structure on a separated jet burner in reacting and non-reacting
flows. Effects of deflection jets in an aligned configuration of three round jets are emphasized. The idea is based on the
confinement of a central jet of fuel by two side jets of oxygen to improve mixing, to control flame stability, and to reduce
pollutant emissions. The fields of mean velocity and fluctuation intensity were measured using Particle Image Velocimetry.
The deflection of jets has a considerable effect on the dynamic behavior and on the flame characteristics. Results showed
that the deflection of jets favors mixing and accelerates merging and combining of jets to a single one. Measurements in reacting
flow showed a high influence of combustion on dynamic fields. Compared to non-reactive case, in combustion, larger radial
expansion and higher velocity were observed, particularly, above the stabilization point of the flame. 相似文献
36.
A spinning drop tensiometer was used to measure the interfacial tension between the coexisting phases of mixtures of low molecular weight polypropylene glycol, Mw = 1000, and polyethylene glycol, Mw = 300, 400, or 550. Two types of experiments gave concordant interfacial tensions. First, the static analysis of the equilibrium diameter of cylindrical drops according to Vonnegut and, second, Tomotika's dynamic analysis of Rayleigh instabilities caused by a sharp decrease of the angular speed. The end-pinching process also lead to the break-up of the drops and it was characterized by a rapid expansion of the hemispherical ends followed by a slower pinching step. The pinching rate increases as the final angular speed decreases while the growth rate of Rayleigh instabilities shows no definite trends in the range 118-245 rad · s?1. It is shown that the end-pinching of long cylindrical drops can be analyzed in terms of short fiber retraction to get the interfacial tension. © 1995 John Wiley & Sons, Inc. 相似文献
37.
: Ortho-substituted diaryloxide tricarbonylchromium (O) complexes PhOAr-Cr (CO)3, treated with carbanions Nu?, give, after acid quenching, paradisubstituted complexes NuAr-Cr (CO)3 via a 1,3-hydride migration followed by elimination of phenol : the overall sequence of the reaction consists in a regioselective substitution of the phenoxy group by the nucleophile. 相似文献
38.
Scherl A Zimmermann-Ivol CG Di Dio J Vaezzadeh AR Binz PA Amez-Droz M Cochard R Sanchez JC Glückmann M Hochstrasser DF 《Rapid communications in mass spectrometry : RCM》2005,19(5):605-610
Acquisition of tandem mass spectra from peptides or other analytes deposited on non-conductive membranes is inhibited on instruments combining matrix-assisted laser desorption/ionization with tandem time-of-flight analyzers (MALDI-TOF/TOF) due to a charging effect. A thin layer of gold renders the membrane conductive. This allows adequate data acquisition on MALDI-TOF/TOF systems. Therefore, this methodology extends the capacity of the molecular scanner concept to tandem mass spectrometry. 相似文献
39.
[structure: see text] Synthesis of gamma-amino acids, important building blocks in bioorganic and natural product chemistry, is accomplished using a stereoselective carbon-carbon bond construction of the chiral amine. Alkyl iodides and chiral hydrazones with protected alcohol functionality are coupled via highly diastereoselective photolytic Mn-mediated addition to the C=N bond, providing access to enantiomerically pure multifunctional chiral alpha-branched amines. Reductive N-N bond cleavage and alcohol oxidation provides alpha-substituted gamma-amino acid building blocks for tubulysin D. 相似文献
40.
Akapo SO Wegner M Mamangun A McCrea C Asif M Dussex JC 《Journal of chromatography. A》2004,1046(1-2):211-216
The levels of 2-amino-9H-pyrido[2,3-b]indole (AalphaC or 2-amino-alpha-carboline), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAalphaC or 2-amino-3-methyl-alpha-carboline), 9H-pyrido[3,4-b]indole (norharman), and 1-methyl-pyrido[3,4-b]indole (harman) have been determined in the mainstream smoke condensate from three reference cigarettes, namely Kentucky reference 1R5F, Kentucky reference 2R4F, and CORESTA CM4. The amino-alpha-carbolines, and norharman and harman (beta-carbolines) can be classified as heterocyclic aromatic amines (HAAs) and are listed as biologically active agents in the mainstream smoke of cigarettes. For the analysis, the mainstream smoke condensate from cigarettes was collected on a filter pad, the analytes were isolated using solid-phase extraction (SPE), and quantified without derivatization on a GC-MS. Total amounts of carbolines found in the condensate increased from ultralight 1R5F to full-flavor CM4 cigarettes. The level of harman was about 250 ng/cigarette for the 1R5F cigarette and about 1025 ng/cigarette for the CM4 cigarette. Norharman was typically three times more abundant than harman. The AalphaC was found at about 10 times lower level compared to harman, and MeAalphaC was about 50 times lower than harman. The use of reference cigarettes can provide a common measure for laboratories to assess carboline amounts among cigarette brands. 相似文献