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Nunes FM Barros-Filho BA de Oliveira MC Andrade-Neto M de Mattos MC Mafezoli J Pirani JR 《Magnetic resonance in chemistry : MRC》2005,43(10):864-866
One- and two-dimensional NMR experiments were used for the unambiguous assignment of the (1)H and (13)C NMR chemical shifts of the furoquinoline alkaloid maculine (1) and the new furanocoumarin 3,8-dimethoxyfuro[3,2-g]coumarin (2). 相似文献
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Glaydston Mattos Ribeiro Guy Desaulniers Jacques Desrosiers Thibaut Vidal Bruno Salezze Vieira 《Journal of Heuristics》2014,20(6):677-708
Onshore oil fields may contain hundreds of wells that use sophisticated and complex equipments. These equipments need regular maintenance to keep the wells at maximum productivity. When the productivity of a well decreases, a specially-equipped vehicle called a workover rig must visit this well to restore its full productivity. Given a heterogeneous fleet of workover rigs and a set of wells requiring maintenance, the workover rig routing problem (WRRP) consists of finding rig routes that minimize the total production loss of the wells over a finite horizon. The wells have different loss rates, need different services, and may not be serviced within the horizon. On the other hand, the number of available workover rigs is limited, they have different initial positions, and they do not have the same equipments. This paper presents and compares four heuristics for the WRRP: an existing variable neighborhood search heuristic, a branch-price-and-cut heuristic, an adaptive large neighborhood search heuristic, and a hybrid genetic algorithm. These heuristics are tested on practical-sized instances involving up to 300 wells, 10 rigs on a 350-period horizon. Our computational results indicate that the hybrid genetic algorithm outperforms the other heuristics on average and in most cases. 相似文献
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The reaction of deactivated arenes with tribromoisocyanuric acid (TBCA) in 98% H2SO4 produced bromoarenes in good yields. The acidity of the medium controls the strength of the brominating agent and the amount of polybrominated products. DFT calculations at B3LYP/6-311++G∗∗ level showed that the protonated TBCA (a superelectrophilic species) can easily transfer Br+ to deactivated arenes, in order to decrease internal charge-charge repulsion. 相似文献
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H.S. da Costa Mattos F.E.G. Chimisso 《International Journal of Solids and Structures》2011,48(1):144-152
Due to its low density and high strength, HMPE (high modulus polyethylene) fibres are being increasingly used in synthetic ropes for offshore mooring. Nevertheless, the occurrence of creep at sea temperature can be a shortcoming for its practical use. Creep tests performed at different load levels in a sub-system of the HMPE rope (yarn) are frequently used as a first step to obtain some information about the susceptibility to creep deformation at a given temperature. The present paper is concerned with the phenomenological modelling of creep tests in HMPE yarns. In this macroscopic approach, besides the classical variables (stress, total strain), an additional scalar variable related with the damage induced by creep process is introduced. An evolution law is proposed for this damage variable. The predicted lifetimes and elongations of HMPE specimens in creep tests at different load levels and room temperature are compared with experimental results showing a good agreement. 相似文献
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Marcio C. S. Mattos Antonio M. Sanseverino 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1203-1208
The addition of thioacids and thiophenol to (R)-limonene catalyzed by Amberlyst-15 produced the corresponding 9-thioester- or 9-thioether-p-menthene chemo- and regioselectively. 相似文献