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Young Derek S. Chen Xi Hewage Dilrukshi C. Nilo-Poyanco Ricardo 《Advances in Data Analysis and Classification》2019,13(4):1053-1082
Advances in Data Analysis and Classification - Finite mixtures of (multivariate) Gaussian distributions have broad utility, including their usage for model-based clustering. There is increasing... 相似文献
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In many generic combustion models, one finds that a combustionwave will develop with a specific wave speed. However, thereare possible initial temperature profiles which do not evolveinto such waves, but rather die out to the ambient temperature.There can exist, in some models, a clear distinction betweenthose initial conditions that do evolve into combustion wavesand those that do not; this is sometimes referred to as thewatershed initial condition. When fuel consumption is consideredto be negligible, analytical methods can be used to obtain theexact watershed. In this paper, we consider the problem of determiningpseudo-watersheds and ascertaining the relationship betweenthese pseudo-watersheds and the exact watersheds. In the processa novel weight-function approach for infinite spatial domainsis developed. 相似文献
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Georgiy Akopov Nethmi W. Hewage Philip Yox Gayatri Viswanathan Shannon J. Lee Liam P. Hulsebosch Sarah D. Cady Alexander L. Paterson Frdric A. Perras Wenqian Xu Kui Wu Yaroslav Mudryk Kirill Kovnir 《Chemical science》2021,12(44):14718
An innovative method of synthesis is reported for the large and diverse (RE)6(TM)x(Tt)2S14 (RE = rare-earth, TM = transition metals, Tt = Si, Ge, and Sn) family of compounds (∼1000 members, ∼325 contain Si), crystallizing in the noncentrosymmetric, chiral, and polar P63 space group. Traditional synthesis of such phases involves the annealing of elements or binary sulfides at elevated temperatures. The atomic mixing of refractory components technique, presented here, allows the synthesis of known members and vastly expands the family to nearly the entire transition metal block, including 3d, 4d, and 5d TMs with oxidation states ranging from 1+ to 4+. Arc-melting of the RE, TM, and tetrel elements of choice forms an atomically-mixed precursor, which readily reacts with sulfur providing bulk powders and large single crystals of the target quaternary sulfides. Detailed in situ and ex situ experiments show the mechanism of formation, which involves multiphase binary sulfide intermediates. Crystal structures and metal oxidation states were corroborated by a combination of single crystal X-ray diffraction, elemental analysis, EPR, NMR, and SQUID magnetometry. The potential of La6(TM)x(Tt)2S14 compounds for non-linear optical applications was also demonstrated.Synthesis from atomically-mixed precursors opens up a phase space to hundreds of chiral and polar sulfide semiconductors with almost any transition metal in variable oxidation states. 相似文献
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Jinasena W. Hewage 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2014,68(6):1-11
Molecular dynamics simulation (MD) with Sutton-Chen potential for palladium-palladium, nickel-nickel and palladium-nickel interactions has been used to generate the minimum energy structures and to study the thermodynamic and dynamic properties of mixed transition metal cluster motifs of Ni n Pd(13?n) for n ≤ 13. Thirteen particle icosahedral clusters of neat palladium and nickel atoms were first reproduced accordingly with the results in literature. Then in the palladium icosahedra, each palladium atom has been successively replaced by nickel atom. Calculation is repeated for both palladium-centered and nickel-centered clusters. It is found that the nickel-centered clusters are more stable than the palladium-centered clusters and cohesive energy increases along the palladium end to nickel end. Phase transition of each cluster from one end-species to the other end-species is studied by means of caloric curve, root mean square bond fluctuation and heat capacity. Trend in variation of melting temperature is opposite to the energy trend. Palladium-centered cluster shows a premelting at low temperature due to the solid-solid structural transition. Species-centric order parameters developed by Hewage and Amar is used to understand the dynamic behavior in the solid-solid transition of palladium-centered cluster to more stable nickel-centered cluster (premelting). This species-centric order parameter calculation further confirmed the stability of nickel-centered species over those of palladium-centered species and solid-solid structural transition at low temperature. 相似文献
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Marc Bria Alan Cooper Shanika Gunatilaka Hewage Margaret Nutley 《Tetrahedron letters》2007,48(48):8430-8433
This Letter, describes the complexation of α-, β- and γ-cyclodextrins (1-3) with TTF derivative 4 in water. In particular, we show using 1H, 13C NMR, UV-vis spectroscopy and isothermal titration calorimetry that β-cyclodextrin 2 forms an effective complex with 4. Complex 2·4 can be conveniently disassembled upon the addition of 1-adamantanol. 相似文献
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