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911.
Variable neighbourhood search: methods and applications 总被引:1,自引:0,他引:1
Pierre Hansen Nenad Mladenović José A. Moreno Pérez 《Annals of Operations Research》2010,175(1):367-407
Variable neighbourhood search (VNS) is a metaheuristic, or a framework for building heuristics, based upon systematic changes of neighbourhoods both in descent phase, to find a local minimum, and in perturbation phase to emerge from the corresponding valley. It was first proposed in 1997 and has since then rapidly developed both in its methods and its applications. In the present paper, these two aspects are thoroughly reviewed and an extensive bibliography is provided. Moreover, one section is devoted to newcomers. It consists of steps for developing a heuristic for any particular problem. Those steps are common to the implementation of other metaheuristics. 相似文献
912.
Structural control is becoming an attractive alternative for enhanced performance of civil engineering structures subject
to seismic and wind loads. However, in order to guarantee stability and performance of structures when implemented with a
passive or active control technique, there is a need to include information of uncertainty in the structural models due to
the fact that civil engineering structures are time variant and nonlinear. These variations in the structure are often due
to parameters such as variable live loads and inelastic behavior and, in cases, may be modeled as parametric uncertainty.
The design of an optimal tuned mass damper (TMD) for a one degree-of-freedom (SDOF) system with parametric uncertainty is
presented in this paper. The optimization of the connection between the absorber and the primary structure is cast as a constant
feedback problem which is solved using structured singular value, μ, synthesis with D-K iteration and decentralized H
∞ design. Results are presented of the TMD that minimize the harmonic response of the primary structure represented by a set
of systems within an uncertainty set. 相似文献
913.
Elías Moreno F.J. Girón F.J. Vázquez-Polo M.A. Negrı´n 《European Journal of Operational Research》2010
This paper deals with medical treatments comparison from the cost-effectiveness viewpoint. A decision theory scheme is considered, where the decision space is the set of treatments involved, the space of states of nature consists of the respective net benefits of the treatments, and the utility function is one of two possible candidates. A first candidate is the one typically used in the literature on cost-effectiveness analysis, for which the utility of a decision is proportional to the net benefit gain, and a second one is of the type 0–1, which penalizes the wrong decisions with a fixed quantity. Their associated optimal decision rules, both frequentist and Bayesian, are analyzed and compared via frequentist evaluation of their performance, and the conclusion is that the latter beats the former in the sense of choosing the optimal treatment more often than any other, thus minimizing the proportion of wrong decisions. Illustrations with simulated and real data are provided. 相似文献
914.
M. Quintero E. Quintero E. Moreno P. Grima N. Marchan G.E. Delgado M.A. Macías C.A. Ponce 《Journal of magnetism and magnetic materials》2009,321(4):295-299
Measurements of magnetic susceptibility χ, in the temperature range from 2 to 300 K, and of magnetization M vs. applied magnetic field B, up to 5 T, at various temperatures were made on polycrystalline samples of the Mn2GeTe4 compound. It was found that Mn2GeTe4 has a Néel temperature TN of about 135 K, shows mainly antiferromagnetic behavior with a very weak superimposed ferromagnetic component that is attributed to spin canting. Also, the magnetic results suggest that a possible spin-glass transition takes place at Tf≈45 K. The spin-glass order parameter q(T), determined from the susceptibility data, was found to be in agreement with the prediction of conventional spin-glass theory. The M vs. B results indicated that bound magnetic polarons (BMPs) occur in the compound, and that the effects from BMPs disappear at approximately 80 K. The M vs. B curves were well fitted by a Langevin type of equation, and the variation of the fitting parameters determined as a function of temperature. Using a simple spherical model, the radius of the BMP in the material was found to be about 27 Å; this value is similar to the effective Bohr radius for an acceptor in the II-IV-V2 and I-III-VI2 ternary semiconductor compounds. 相似文献
915.
We exploit the relationship between the space components Tij of the energy–momentum tensor and the supercurrent to discuss the connection between the BPS equations and the vanishing of the components of the stress tensor in various supersymmetric theories with solitons. Using the fact that certain combination of supercharges annihilate BPS states, we show that Tij=0 for kinks, vortices and dyons, displaying the connection between supersymmetry and non-interacting BPS solitons. 相似文献
916.
Gustavo A. Moreno 《Physics letters. A》2009,373(42):3897-3900
We prove that the ground state momentum distribution of a one-dimensional system of impenetrable bosons exhibits a k−4 tail for any confining potential. We also derive an expression for easily computing the asymptotic occupation numbers and verify our results with an exact numerical approach. 相似文献
917.
A radiographic method is proposed and then applied to infer the continuum part of the hard X-ray spectrum of a 4.7 kJ Plasma Focus from differential absorption measurements on metals. Copper, nickel, titanium and silver samples with thicknesses spanning between 0.1 and 10 mm were employed as filters. The X-ray radiation was detected using a standard radiographic screen-film system. The results show the presence of a dominant peak around 75 keV with significant spectral components in the range of 40 to 200 keV. The method is easy to follow, inexpensive, and allows for calibrated, single shot, spectral measurements. 相似文献
918.
Pedro Cobo Silvia Murillo-Cuesta Antonio Moreno Isabel Varela-Nieto 《Applied Acoustics》2009,70(8):1034-1040
Previous work on the acoustic design of small reverberant chambers for studies on laboratory animals has paid, in general, more attention to the frequency response at certain points in their interior. These designs aimed to provide a frequency response as flat as possible at the receivers, thus avoiding unpleasant spectral coloration effects. However, an equally important, and frequently neglected, aspect is to set an acoustic field as spatially uniform as possible inside the zone where the animals are to be placed during the exposure to noise. Here, an optimization procedure is described to calculate the proportions of the chamber dimensions that confers the highest sound level with the minimum mean squared deviation averaged in a given area inside the chamber. In addition, new stimuli have been designed with a high-pass filtering and linear with frequency gain. These stimuli were intended to adapt the characteristics of the exposing noise to the rodent hearing spectrum, displaced toward higher frequencies than the hearing frequency band of humans. 相似文献
919.
J.J. Carvajal M.C. Pujol M. Aguiló J.R. Vázquez de Aldana P. Moreno T. Trifonov R. Alcubilla J. Ferré-Borrull L.F. Marsal R. Macovez 《Journal of luminescence》2009,129(12):1441-1447
We revisited two different strategies to fabricate 1D photonic crystals of nonlinear optical dielectric materials based on ultrafast laser ablation of the surface of an RbTiOPO4 crystal, and selective etching of ferroelectric domains of the surface of a periodically poled LiNbO4 crystal. We evaluated their behaviour as Bragg diffraction gratings. We also presented the recent advances we developed in a new procedure of fabrication of 2D and 3D photonic crystals of KTiOPO4 (KTP) grown on the surface of a KTP substrate by liquid phase epitaxial means within the pores of a silicon macroporous template. Optical, structural, morphological, and compositional characterization for the photonic crystals produced through this technique are presented. 相似文献
920.
Harrison N Alver U Goodrich RG Vekhter I Sarrao JL Pagliuso PG Moreno NO Balicas L Fisk Z Hall D Macaluso RT Chan JY 《Physical review letters》2004,93(18):186405
de Haas-van Alphen measurements on Ce(x)La(1-x)MIn(5) yield contrasting types of behavior that depend on whether M=Co and Ir or M=Rh. A stronger x-dependent scattering in the case of M=Co and Ir is suggestive of a stronger relative coupling, J/W, of the conduction electrons to the 4f electrons, which would then account for the development of a heavy composite Fermi-liquid state as x-->1. The failure of a composite Fermi-liquid state to form for any x in the case of M= Rh is shown to be inconsistent with theoretical models that propose antiferromagnetism to result from spin-density-wave formation. 相似文献