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111.
M Gallego M Laguna R Martí A Duarte 《The Journal of the Operational Research Society》2013,64(5):724-734
We propose new heuristic procedures for the maximally diverse grouping problem (MDGP). This NP-hard problem consists of forming maximally diverse groups—of equal or different size—from a given set of elements. The most general formulation, which we address, allows for the size of each group to fall within specified limits. The MDGP has applications in academics, such as creating diverse teams of students, or in training settings where it may be desired to create groups that are as diverse as possible. Search mechanisms, based on the tabu search methodology, are developed for the MDGP, including a strategic oscillation that enables search paths to cross a feasibility boundary. We evaluate construction and improvement mechanisms to configure a solution procedure that is then compared to state-of-the-art solvers for the MDGP. Extensive computational experiments with medium and large instances show the advantages of a solution method that includes strategic oscillation. 相似文献
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Denise Tofanello Gimenes Polyana Fernandes Pereira Rafael Rodrigues Cunha Rodrigo Amorim Bezerra da Silva Rodrigo Alejandro Abarza Munoz Eduardo Mathias Richter 《Electroanalysis》2012,24(9):1805-1810
In this study, we describe for the first time the application of an internal standard method to compensate for random errors associated with the injection procedure in batch injection analysis (BIA) systems with multiple pulse amperometric detection. A sequence of potential pulses was selected in such a way that the internal standard (IS) compound was detected individually at one potential pulse and both the IS and analyte, were detected at another potential pulse. The current ratio (IIS+analyte/IIS) was used in the construction of the calibration curve and then to compensate for random errors. The use of disposable syringes or manual pipettes in BIA systems increases the robustness of the method and dispenses with skilled operators. 相似文献
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115.
Haroldo G. Santos Túlio A. M. Toffolo Rafael A. M. Gomes Sabir Ribas 《Annals of Operations Research》2016,239(1):225-251
This work presents integer programming techniques to tackle the problem of the International Nurse Rostering Competition. Starting from a compact and monolithic formulation in which the current generation of solvers performs poorly, improved cut generation strategies and primal heuristics are proposed and evaluated. A large number of computational experiments with these techniques produced the following results: the optimality of the vast majority of instances was proved, the best known solutions were improved by up to 15 % and strong dual bounds were obtained. In the spirit of reproducible science, all code was implemented using the Computational Infrastructure for Operations Research. 相似文献
116.
This work deals with the selective incorporation of reactive isocyanate groups into methyl cellulose in order to be used as reactive thickening agent in castor oil. Resulting gel-like dispersions may have potential applications as green lubricating greases formulated from renewable resources. Two different isocyanate-functionalized methyl cellulose-based polymers were obtained by reaction of methyl cellulose with 1,6-hexamethylene diisocyanate. The functionalization degree, from fully functionalized to a certain number of free hydroxyl groups (58:36:6 ratio between –OMe, –NCO and free –OH groups), was controlled by modifying the reagents molar ratio. These polymers were characterized through nuclear magnetic resonance of protons (1H-NMR), Fourier transform infrared spectroscopy and thermogravimetric analysis (TGA). Thermal and rheological responses of oleogels prepared by dispersing these polymers in castor oil were studied by means of TGA analysis and small-amplitude oscillatory shear measurements. The evolution of linear viscoelasticity functions with frequency of the oleogel containing isocyanate-functionalized methyl cellulose with lower –NCO content is quite similar to that found for traditional lithium lubricating greases. In relation to long-term stability of these oleogels, the values of viscoelastic functions significantly increase during the first 7 days of ageing and then remain almost constant. 相似文献
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Nail Zabirov Sergej Kashevarov Rafael Cherkasov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract N-(thio)carbonyl(thio)amidophosphates, their open-chain and crown-containing analogues with a C (X) NHP (Y) fragments are NH acids with pKa 8–11 and the effective complexing agents for “soft” ion metals. 相似文献
119.
Julia Vallejo Alejandro Pascual‐Álvarez Dr. Joan Cano Dr. Isabel Castro Prof. Dr. Miguel Julve Prof. Dr. Francesc Lloret Dr. J. Krzystek Prof. Dr. Giovanni De Munno Dr. Donatella Armentano Prof. Dr. Wolfgang Wernsdorfer Dr. Rafael Ruiz‐García Dr. Emilio Pardo 《Angewandte Chemie (International ed. in English)》2013,52(52):14075-14079
120.
We study numerically the “analyticity breakdown” transition in 1-dimensional quasi-periodic media. This transition corresponds physically to the transition between pinned down and sliding ground states. Mathematically, it corresponds to the solutions of a functional equation losing their analyticity properties. We implemented some recent numerical algorithms that are efficient and backed up by rigorous results so that we can compute with confidence even close to the breakdown. We have uncovered several phenomena that we believe deserve a theoretical explanation: (A) The transition happens in a smooth surface. (B) There are scaling relations near breakdown. (C) The scaling near breakdown is very anisotropic. Derivatives in different directions blow up at different rates. Similar phenomena seem to happen in other KAM problems. 相似文献