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21.
Rafael Caballero Mercedes González Flor M Guerrero Julián Molina Concepción Paralera 《European Journal of Operational Research》2007
In this work we present a multiobjective location routing problem and solve it with a multiobjective metaheuristic procedure. In this type of problem, we have to locate some plants within a set of possible locations to meet the demands of a number of clients with multiple objectives. This type of model is used to solve a problem with real data in the region of Andalusia (Spain). Thus, we study the location of two incineration plants for the disposal of solid animal waste from some preestablished locations in Andalusia, and design the routes to serve the different slaughterhouses in this region. This must be done while taking into account certain economic objectives (start-up, maintenance, and transport costs) and social objectives (social rejection by towns on the truck routes, maximum risk as an equity criterion, and the negative implications for towns close to the plant). 相似文献
22.
Ivan Nunes da Silva Wagner Caradori do AmaralLucia Valeria de Arruda 《Applied Mathematical Modelling》2007
This paper presents an efficient approach based on recurrent neural network for solving nonlinear optimization. More specifically, a modified Hopfield network is developed and its internal parameters are computed using the valid subspace technique. These parameters guarantee the convergence of the network to the equilibrium points that represent an optimal feasible solution. The main advantage of the developed network is that it treats optimization and constraint terms in different stages with no interference with each other. Moreover, the proposed approach does not require specification of penalty and weighting parameters for its initialization. A study of the modified Hopfield model is also developed to analyze its stability and convergence. Simulation results are provided to demonstrate the performance of the proposed neural network. 相似文献
23.
A. E. S. Vives S. Moreira S. M. B. Brienza O. L. A. Zucchi V. F. Nascimento Filho 《Journal of Radioanalytical and Nuclear Chemistry》2006,270(1):147-153
Summary The objective of this study was to use synchrotron radiation total reflection X-ray fluorescence analysis (SR-TXRF) for the
determination of metals and other elements in food available to the population in commercial establishments, in order to evaluate
the risks of contamination by these products. The analyzed species were vegetables, leafy vegetables, fruits, cereal and grain.
The results indicated that some species were contaminated by Cr, Cu, Zn and Pb with concentrations much higher than the reference
values. 相似文献
24.
This work describes the first catalytic bismuth-promoted synthesis of polysubstituted guanidines in good yields through the guanylation reaction of N-benzoyl or N-phenylthioureas with primary and secondary amines, but now employing equimolar amounts of each organic reagent. Both bismuth iodine and bismuth nitrate were efficient as inorganic thiophiles at only 5 mol % in relation to substrates, being the first example of inorganic thiophiles acting in guanylation at catalytic levels. 相似文献
25.
26.
Rafael Tiedra de Aldecoa 《Annales Henri Poincare》2006,7(1):105-124
Although many physical arguments account for using a modified definition of time delay in multichannel-type scattering processes,
one can hardly find rigorous results on that issue in the literature. We try to fill in this gap by showing, both in an abstract
setting and in a short-range case, the identity of the modified time delay and the Eisenbud-Wigner time delay in waveguides.
In the short-range case we also obtain limiting absorption principles, state spectral properties of the total Hamiltonian,
prove the existence of the wave operators and show an explicit formula for the S-matrix. The proofs rely on stationary and commutator methods.
Communicated by Yosi Avron
submitted 12/04/05, accepted 13/05/05 相似文献
27.
L. G. Marcassa V. A. Nascimento L. L. Caliri A. Caires D. V. Magalhães V. S. Bagnato 《Laser Physics》2006,16(12):1722-1725
In this paper, we report observation of an enhancement of the ground state molecule Rb2 formation in a Rb magneto-optical trap due to a photoassociation laser. Such an enhancement effect is due to flux enhancement of atomic pairs at short internuclear distances. Our experimental observations consist in the measurement of the molecular formation rate constant due to a probe laser as a function of the trap laser intensity. The results are compared with a simple semi-classical model, showing good agreement. We conclude that the production of cold Rb2 may be enhanced using appropriate laser parameters; this may be useful for future experiments involving production and trapping of ultracold ground state molecules. 相似文献
28.
29.
Rafael Ortega 《Journal of Dynamics and Differential Equations》1992,4(4):651-665
This paper gives sufficient conditions for the existence of periodic solutions of twist type of a time-dependent differential equation of the second order. The concept of periodic solution of twist type is defined in terms of the corresponding Birkhoff normal form and, in particular, implies that the solution is Lyapunov stable. Some applications to nonlocal problems are given. 相似文献
30.
The electrocatalytic oxidation of 2-propanol was investigated using on line differential electrochemical mass spectrometry (DEMS) on electrodeposited Pt and an arrange of bimetallics: Pt0.84Rh0.16, Pt0.70Rh0.30, Pt0.55Rh0.45. It has been observed that the Pt0.84Rh0.16 bimetallic electrode presented the best catalytic activity for 2-propanol electrochemical oxidation. Since 2-propanol is a secondary alcohol, only acetone and CO2 are produced. The total yield of CO2 and acetone has been determined from the DEMS measurements. It is found that acetone is the major product, as reported before for other electrodes. The acetone and CO2 yield depends on the electrode composition. High amount of rhodium in the electrode composition strongly diminish the reaction rate as indicated by the decrease of both the acetone and CO2 yield. However, acetone inhibition is much more intense. The only bimetallic electrode that presents considerable mass spectroscopy signals intensity for CO2 and acetone is the Pt0.84Rh0.16 electrode. This electrode shows a slight increase in CO2 selectivity, compared to the other electrodes studied in this work. Only very low coverages of stable adsorbates were present during the reaction. Two and one carbon adsorbate were observed for all the electrodes. Three carbon adsorbates were detected only for the Pt0.84Rh0.16 electrode. Therefore, acetone production does not require a stable adsorbate. 相似文献