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61.
Philip J. Burke William Clegg Terence C. Jenkins Ian T. Meikle 《Tetrahedron letters》2010,51(30):3918-7450
Treatment of the N-nitroaryl-3-hydroxypiperidine derivatives 12 and 13 with thionyl chloride afforded the corresponding N-aryl-2-chloromethylpyrrolidines 5 and 15 via a ring-contraction process involving an intermediate aziridinium ion. 相似文献
62.
Jorge A. Soria-Alcaraz Gabriela Ochoa Jerry Swan Martin Carpio Hector Puga Edmund K. Burke 《European Journal of Operational Research》2014
Course timetabling is an important and recurring administrative activity in most educational institutions. This article combines a general modeling methodology with effective learning hyper-heuristics to solve this problem. The proposed hyper-heuristics are based on an iterated local search procedure that autonomously combines a set of move operators. Two types of learning for operator selection are contrasted: a static (offline) approach, with a clear distinction between training and execution phases; and a dynamic approach that learns on the fly. The resulting algorithms are tested over the set of real-world instances collected by the first and second International Timetabling competitions. The dynamic scheme statistically outperforms the static counterpart, and produces competitive results when compared to the state-of-the-art, even producing a new best-known solution. Importantly, our study illustrates that algorithms with increased autonomy and generality can outperform human designed problem-specific algorithms. 相似文献
63.
Aleksandra Swiercz Edmund K. Burke Mateusz Cichenski Grzegorz Pawlak Sanja Petrovic Tomasz Zurkowski Jacek Blazewicz 《Central European Journal of Operations Research》2014,22(3):567-589
This paper introduces a new approach to applying hyper-heuristic algorithms to solve combinatorial problems with less effort, taking into account the modelling and algorithm construction process. We propose a unified encoding of a solution and a set of low level heuristics which are domain-independent and which change the solution itself. This approach enables us to address NP-hard problems and generate good approximate solutions in a reasonable time without a large amount of additional work required to tailor search methodologies for the problem in hand. In particular, we focused on solving DNA sequencing by hybrydization with errors, which is known to be strongly NP-hard. The approach was extensively tested by solving multiple instances of well-known combinatorial problems and compared with results generated by meta heuristics that have been tailored for specific problem domains. 相似文献
64.
KM Varier AM Vinodkumar NVSV Prasad PV Madhusudhana Rao DL Sastry Lagy T Baby MC Radhakrishna NG Puttaswamy JJ Das P Sugathan N Madhavan AK Sinha DO Kataria 《Pramana》1999,53(3):529-533
Large enhancements have been observed in the sub-barrier fusion cross sections for Ti+Ni systems in our previous studies.
Coupled channel calculations incorporating couplings to 2+ and 3− states failed to explain these enhancements completely. A possibilty of transfer channels contributing to the residual enhancements
had been suggested. In order to investigate the role of relevant transfer channels, measurements of one- and two-nucleon transfer
were carried out for 46,48Ti+61Ni systems. The present paper gives the results of these studies. 相似文献
65.
This paper concerns smoothing by infimal convolution for two large classes of functions: convex, proper and lower semicontinous as well as for (the nonconvex class of) convex-composite functions. The smooth approximations are constructed so that they epi-converge (to the underlying nonsmooth function) and fulfill a desirable property with respect to graph convergence of the gradient mappings to the subdifferential of the original function under reasonable assumptions. The close connection between epi-convergence of the smoothing functions and coercivity properties of the smoothing kernel is established. 相似文献
66.
67.
We propose a picture of Wigner function scars as a sequence of concentric rings along a two-dimensional surface inside a periodic orbit. This is verified for a two-dimensional plane that contains a classical hyperbolic orbit of a Hamiltonian system with 2 degrees of freedom. The stationary wave functions are the familiar mixture of scarred and random waves, but the spectral average of the Wigner functions in part of the plane is nearly that of a harmonic oscillator and individual states are also remarkably regular. These results are interpreted in terms of the semiclassical picture of chords and centers. 相似文献
68.
de la Vaissiere C Luth V Abrams GS Amidei D Baden AR Barklow T Boyarski AM Boyer J Breidenbach M Burchat P Burke DL Butler F Dillon JW Dorfan JM Feldman GJ Gidal G Gladney L Gold MS Goldhaber G Golding LG Hanson G Haggerty J Herrup D Himel T Hollebeek RJ Innes WR Jaros JA Juricic I Kadyk JA Klein SR Lankford AJ Larsen RR LeClaire BW Levi ME Lockyer NS Matteuzzi C Nelson ME Ong RA Perl ML Richter B Ross MC Rowson PC Schaad T Schellman H Schmidke WB Sheldon PD Trilling GH Yelton JM Wood DR 《Physical review letters》1985,54(19):2071-2074
69.
Anthony J. Burke Elisabete da Palma Carreiro Nuno M.M. Moura Ana Isabel Rodrigues 《Journal of organometallic chemistry》2007,692(22):4863-4874
In our quest to find new ligands for highly stereoselective reactions, we tested a variety of chiral non-racemic pseudo-C2 symmetric bis-oxazolines derived from malonic acid containing an arylidene bridge unit (and appropriately termed Arylid-Box) in the catalytic asymmetric cyclopropanation (CAP) reaction of styrene and ethyl diazoacetate using between only 1-2 mol% of a Cu(I) pre-catalyst. Some very good e.e.s (up to 86%), were obtained. It was possible to isolate 10a′-[Cu(CH3CN)4]PF6 which existed as a bench stable solid that proved to be more efficient than the catalyst prepared in situ. Cu(I) pre-catalysts were used for the first time in the CAP reaction with the Isbut-Box ligands 13a and 13b and, although, the e.e.s were better for ligand 13a using these pre-catalysts, in the case of ligand 11b this was not the case. Spectroscopic studies (UV-Vis and 1H NMR) were carried out to gain an insight into the nature of the catalytic species at work so that the conditions could be optimised giving better results. Some theoretical studies were conducted to try to explain the better enantioselectivities obtained using Evans’ tert-Box-Cu(I) complex over our complex. 相似文献
70.
The underlying metal was observed to corrode when a ruthenium dioxide-coated titanium electrode was anodized in an aqueous methanol solution. With a similarly coated platinum electrode peaks were observed on the voltammogram below 1.0 V which were attributed to methanol oxidation on the underlying metal. This effect was more pronounced when the electrode was subjected during cycling to potentials close to 0 V. Rapid oxidation of methanol on RuO2 was observed at potentials above 1.0 V, the rate at a given potential increasing in an approximately linear manner with increasing alcohol concentration. The rate of reaction also increased with increasing temperature and increasing surface roughness. Tafel slope values were rather high (>100 mV decade?1) and a mechanism involving anodically generated species such as OHads was proposed to account for these results. The variation of activity with pH was similar to that reported earlier for oxygen evolution at these anodes and this was again explained in terms of partial deactivation of the surface due to a combination of proton loss and phosphate ion adsorption at intermediate pH values. The release of carbon dioxide from aqueous solutions of higher alcohols at 25°C confirmed the high oxidizing power of RuO2 anodes. 相似文献