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951.
A multicriteria Boolean programming problem with linear cost functions in which initial coefficients of the cost functions are subject to perturbations is considered. For any optimal alternative, with respect to parameterized principle of optimality “from Condorcet to Pareto”, appropriate measures of the quality are introduced. These measures correspond to the so-called stability and accuracy functions defined earlier for optimal solutions of a generic multicriteria combinatorial optimization problem with Pareto and lexicographic optimality principles. Various properties of such functions are studied and maximum norms of perturbations for which an optimal alternative preserves its optimality are calculated. To illustrate the way how the stability and accuracy functions can be used as efficient tools for post-optimal analysis, an application from the voting theory is considered. 相似文献
952.
953.
Philippe Derreumaux 《Theoretical chemistry accounts》2000,105(1):1-6
The biological activity of a polypeptide strongly depends on its 3D structure. Ab initio prediction of the native structure
from the sequence of amino acids has long motivated the development of an optimum energy model such that interactions present
in the native conformation are stronger than those present in nonnative conformations and of algorithms capable of finding
the basin of lowest free energy among an astronomically large number of possible conformations. Despite recent progress in
our understanding of the factors responsible for both polypeptide stability and formation, computer simulations of polypeptide
models are still far from being practical software tools for biologists. In this work, state-of-the-art computer simulations
aimed at ab initio structure prediction in aqueous solution are reviewed and their strengths and weaknesses are highlighted.
Received: 23 June 1999 / Accepted: 20 September 1999 / Published online: 15 December 1999 相似文献
954.
We characterize the convex envelope of a given function f as the unique solution of a convex programming problem. It allows us to build a sequence of convex and polygonal function
un
that converges uniformly to the convex envelope of f. 相似文献
955.
In this paper, we consider the routing problem described in Mohanty and Cassandras (Ref. 1). As in Ref. 1, we show that the optimal Bernoulli split to minimize mean time in the system is asymptotically independent of the variance of the service time. We give simple proofs of the results in that paper. We exploit the fact that the optimal split to minimize the mean queueing time is variance independent and the special structure of the Karush–Kuhn–Tucker optimality conditions to derive the optimal solution. Apart from being very straightforward, the proofs also give insight into the reason for the existence of the variance-independent asymptotically optimal routing policy. 相似文献
956.
Received February 10, 1997 / Revised version received June 6, 1998 Published online October 9, 1998 相似文献
957.
Particle swarm optimization is a novel evolutionary stochastic global optimization method that has gained popularity in the chemical engineering community. This optimization strategy has been successfully used for several applications including thermodynamic calculations. To the best of our knowledge, the performance of PSO in phase stability and equilibrium calculations for both multicomponent reactive and non-reactive mixtures has not yet been reported. This study introduces the application of particle swarm optimization and several of its variants for solving phase stability and equilibrium problems in multicomponent systems with or without chemical equilibrium. The reliability and efficiency of a number of particle swarm optimization algorithms are tested and compared using multicomponent systems with vapor–liquid and liquid–liquid equilibrium. Our results indicate that the classical particle swarm optimization with constant cognitive and social parameters is a reliable method and offers the best performance for global minimization of the tangent plane distance function and the Gibbs energy function in both reactive and non-reactive systems. 相似文献
958.
Daniel Hemmeter Dr. Ulrike Paap Nicolas Wellnhofer Afra Gezmis Daniel Kremitzl Prof. Dr. Peter Wasserscheid Prof. Dr. Hans-Peter Steinrück Dr. Florian Maier 《Chemphyschem》2023,24(24):e202300612
Recently, we demonstrated that Pt catalyst complexes dissolved in the ionic liquid (IL) [C4C1Im][PF6] can be deliberately enriched at the IL surface by introducing perfluorinated substituents, which act like buoys dragging the metal complex towards the surface. Herein, we extend our previous angle-resolved X-ray photoelectron spectroscopy (ARXPS) studies at complex concentrations between 30 and 5 %mol down to 1 %mol and present complementary surface tension pendant drop (PD) measurements under ultraclean vacuum conditions. This combination allows for connecting the microscopic information on the IL/gas interface derived from ARXPS with the macroscopic property surface tension. The surface enrichment of the Pt complexes is found to be most pronounced at 1 %mol. It also displays a strong temperature dependence, which was not observed for 5 %mol and above, where the surface is already saturated with the complex. The surface enrichment deduced from ARXPS is also reflected by the pronounced decrease in surface tension with increasing concentration of the catalyst. We furthermore observe by ARXPS and PD a much stronger surface affinity of the buoy-complex as compared to the free ligands in solution. Our results are highly interesting for an optimum design of IL-based catalyst systems with large contact areas to the surrounding reactant/product phase, such as in supported IL phase (SILP) catalysis. 相似文献
959.
960.
研究了5种α,α‘-二氧代烯酮环二硫代缩酮类化合物的碳基、碳碳双键、碳硫等一些特征红外光谱,尤其着重研究了共轭体系下的各种特征谱带随化学结构而变化的规律。 相似文献