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101.
Ricardo M. A. Silva Diego M. Silva Mauricio G. C. Resende Geraldo R. Mateus José F. Gonçalves Paola Festa 《Optimization Letters》2014,8(4):1225-1243
This paper presents a new edge-swap heuristic for generating spanning trees with a minimum number of branch vertices, i.e. vertices of degree greater than two. This problem was introduced in Gargano et al. (Lect Notes Comput Sci 2380:355–365, 2002) and has been called the minimum branch vertices problem by Cerulli et al. (Comput Optim Appl 42:353–370, 2009). The heuristic starts with a random spanning tree and iteratively reduces the number of branch vertices by swapping tree edges with edges not currently in the tree. It can be easily implemented as a multi-start heuristic. We report on extensive computational experiments comparing single-start and multi-start variants on our heuristic with other heuristics previously proposed in the literature. 相似文献
102.
Valeriano Antunes de Oliveira Geraldo Nunes Silva 《Numerical Functional Analysis & Optimization》2019,40(8):867-887
It is well-known in optimal control theory that the maximum principle, in general, furnishes only necessary optimality conditions for an admissible process to be an optimal one. It is also well-known that if a process satisfies the maximum principle in a problem with convex data, the maximum principle turns to be likewise a sufficient condition. Here an invexity type condition for state constrained optimal control problems is defined and shown to be a sufficient optimality condition. Further, it is demonstrated that all optimal control problems where all extremal processes are optimal necessarily obey this invexity condition. Thus optimal control problems which satisfy such a condition constitute the most general class of problems where the maximum principle becomes automatically a set of sufficient optimality conditions. 相似文献
103.
Geraldo L. Crossetti Marcos L. Dias Bruno T. Queiroz Luciana P. Silva Cludio M. Ziglio Joo A. S. Bomfim Carlos A. L. Filgueiras 《应用有机金属化学》2004,18(7):331-336
Three isothiocyanate complexes of nickel(II) containing diimine [ArN?C(Me)? C(Me)?NAr]Ni‐ (NCS)2 (1), iminophosphine [Ph2PC6H4CH?NAr]Ni(NCS)2 (2), or diphosphine (dppe)Ni(NCS)2 (3), [Ar = 2, 6‐iPr‐C6H3; dppe = 1, 2‐bis(diphenylphosphine)ethane] were synthesized and examined for ethylene polymerization activated by methylaluminoxane (MAO). Their behavior was compared with those of the corresponding halide analogues [ArN?C(Me)? C(Me)?NAr]NiBr2 (4), [Ph2PC6H4CH?NAr]NiBr2 (5), and (dppe)NiCl2 (6). The diimines showed the highest polymerization activity. Replacement of the halide for the NCS pseudo halide affected the activity and decreased the molecular weight of the polymer formed. The highest molecular weights were obtained with the diimine complexes. Highly branched polyethylenes were obtained with the bulkier complexes 1 and 4. Replacement of the halide for NCS in the diimine complexes also caused an increase in the branching content, whereas the opposite occurs for the iminophosphine complexes. The different activities and behavior of the catalyst systems with halide versus NCS in the polymerization of ethylene and the characteristics of the final products suggest a modification in the active species caused by the non‐chelating ligand. Polymer molecular weight and branching content is dependent on the MAO/Ni molar ratio and on the working temperature. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
104.
We prove that, like in the linear case, there is a canonical prototype of a p-dominated homogeneous polynomial through which every p-dominated polynomial between Banach spaces factors. 相似文献
105.
Geraldo Botelho 《Indagationes Mathematicae》2005,16(2):157-169
In this paper we introduce two properties for ideals of polynomials between Banach spaces and showhow useful they are to deal with several a priori different problems. By investigating these properties we obtain, among other results, new polynomial characterizations of L∞ spaces and characterizations of Banach spaces whose duals are isomorphic to f 1 (Λ). 相似文献
106.
Soraia Lúcia da Silva Mauro Nacif Rocha Geraldo Robson Mateus 《Annals of Operations Research》2002,116(1-4):57-68
The traffic generation models, which describe how the clients use the network services, as well as the mobility models, which describe how clients move within the service area covered by the network, are essential tools for QoS analysis in these environments. In this paper we present the simulation of a new mobility model implemented for the analysis of QoS parameters of a mobile network, such as channel occupation time, handoff and new call blocking probabilities. 相似文献
107.
Serra AC Pineiro M Rocha Gonsalves AM Abrantes M Laranjo M Santos AC Botelho MF 《Journal of photochemistry and photobiology. B, Biology》2008,92(1):59-65
Brominated and iodinated derivatives of 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin were synthesised directly from the corresponding aldehydes. Photophysical and photochemical properties, singlet oxygen formation quantum yields, photobleaching and log P were measured. Cellular uptake measurements and cytotoxicity assays on WiDr and A375 tumour cell lines were performed. 5,10,15,20-Tetrakis(2-bromo-5-hydroxyphenyl)porphyrin showed the best cytotoxicity with values of IC(50) of 113 nM over WiDr cells and 52nM over A375 cells. 相似文献
108.
Fernanda Botelho James Jamison 《Proceedings of the American Mathematical Society》2008,136(4):1397-1402
We characterize generalized bi-circular projections on a minimal norm ideal of operators in where is a separable infinite dimensional Hilbert space.
109.
Elisabete C.B.A. Alegria Emmanuele Fontolan Ana P.C. Ribeiro Maximilian N. Kopylovich Catarina Domingos Ana M. Ferraria Roberta Bertani Ana M. Botelho do Rego Armando J.L. Pombeiro 《Materials Today Chemistry》2017
A simple and clean mechanochemical synthesis at room temperature was employed to prepare CuO-Fe2O3-CoCl2 (100 nm scale), MoO3-V2O5, CuO-CoCl2, Fe2O3-CoCl2, CuO-V2O5, Cu(CH3COO)2-V2O5, Cu(CH3COO)2-MoO3 (1–100 μm scale) 3d metal based dispersed composites with different ratios of components using simple metal salts/oxides and multiwalled carbon nanotubes (CNT) or graphene oxide (GO) additives (CoCl2-CNT, CoCl2-GO). The thus prepared composite materials were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), field emission gun scanning electron microscopy (FEGSEM), energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). XPS analysis revealed no metal redox change upon ball milling treatment, which however promotes metal hydroxylation.The catalytic activity of the prepared composites in the heterogeneous low power microwave-assisted oxidation of cyclohexane with aq. H2O2 at 30 °C was notorious with yields up to 31% and selectivity up to 94% towards cyclohexanol (upon treatment with PPh3) for the CuO-CoCl2-based material. The hydrocarboxylation of cyclohexane with CO, water and K2S2O8 to produce cyclohexanecarboxylic acid bearing one more carbon atom at 60 °C is achieved with yields up to 17% for the reaction performed in the presence of the CuO-CoCl2 catalyst. The clean CuO-CoCl2 (1:2) catalyst preparation and the catalytic reaction (oxidation of cyclohexane) can be achieved in one-pot at low temperature, without any added organic solvent, and by using exclusively the mechanochemical energy input, with a marked 23% yield at 30 °C. 相似文献
110.
Geraldo?Botelho Jamilson?R.?CamposEmail authorView authors OrcID profile 《Monatshefte für Mathematik》2017,183(3):415-435
In this paper we provide a unifying approach to the study of Banach ideals of linear and multilinear operators defined, or characterized, by the transformation of vector-valued sequences. We also investigate the linear and multilinear stabilities of some frequently used classes of vector-valued sequences. Concrete applications are provided. 相似文献