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Local realistic models of enhanced photon detection reproducing quantum mechanical predictions for single photons and approximating closely the quantum mechanical predictions for pairs of correlated photons are discussed. It is shown that Einstein-Podolsky-Rosen-type experiments with three polarizers can easily discriminate such models from ordinary quantum theory. 相似文献
95.
Bianchi I Forlani R Minetto G Peretto I Regalia N Taddei M Raveglia LF 《Journal of combinatorial chemistry》2006,8(4):491-499
An efficient strategy for the solution-phase parallel synthesis of a library of pyrrole-amides is described. Key reactions include functional homologation of beta-ketoesters with a set of aldehydes followed by oxidation to produce a series of differently substituted 1,4-dicarbonyl compounds. Rapid cyclization using a microwave-assisted Paal-Knorr reaction provided a set of 24 pyrrole esters that were further functionalized through a trimethylaluminum-mediated aminolysis to obtain a larger library of 288 diverse pyrrole-3-amides. The tetrasubstitution allows a good exploration of the chemical space around the central pyrrole core. The last step was entirely automated with a Bohdan Myriad personal synthesizer. 相似文献
96.
De Giacomo A Dell'Aglio M Casavola A Colonna G De Pascale O Capitelli M 《Analytical and bioanalytical chemistry》2006,385(2):303-311
Double-pulse laser-induced plasma spectroscopy (DP-LIPS) is applied to submerged targets to investigate its feasibility for
elemental analysis. The role of experimental parameters, such as inter-pulse delay and detection time, has been discussed
in terms of the dynamics of the laser-induced bubble produced by the first pulse and its confinement effect on the plasma
produced by the second laser pulse. The analytical performance of this technique applied to targets in a water environment
are discussed. The elemental analysis of submerged copper alloys by DP-LIPS has been compared with conventional (single-pulse)
LIBS in air. Theoretical investigation of the plasma dynamics in water bubbles and open air has been performed. 相似文献
97.
We consider the problem of optimizing an unknown function given as an oracle over a mixed-integer box-constrained set. We assume that the oracle is expensive to evaluate, so that estimating partial derivatives by finite differences is impractical. In the literature, this is typically called a black-box optimization problem with costly evaluation. This paper describes the solution methodology implemented in the open-source library RBFOpt, available on COIN-OR. The algorithm is based on the Radial Basis Function method originally proposed by Gutmann (J Glob Optim 19:201–227, 2001. https://doi.org/10.1023/A:1011255519438), which builds and iteratively refines a surrogate model of the unknown objective function. The two main methodological contributions of this paper are an approach to exploit a noisy but less expensive oracle to accelerate convergence to the optimum of the exact oracle, and the introduction of an automatic model selection phase during the optimization process. Numerical experiments show that RBFOpt is highly competitive on a test set of continuous and mixed-integer nonlinear unconstrained problems taken from the literature: it outperforms the open-source solvers included in our comparison by a large amount, and performs slightly better than a commercial solver. Our empirical evaluation provides insight on which parameterizations of the algorithm are the most effective in practice. The software reviewed as part of this submission was given the Digital Object Identifier (DOI) https://doi.org/10.5281/zenodo.597767. 相似文献
98.
We present a uniform version of Di Nola Theorem, this enables to embed all MV-algebras of a bounded cardinality in an algebra of functions with values in a single non-standard ultrapower of the real
interval [0,1]. This result also implies the existence, for any cardinal α, of a single MV-algebra in which all infinite MV-algebras of cardinality at most α embed. Recasting the above construction with iterated ultrapowers, we show how to construct such an algebra of values in a definable way, thus providing a sort of “canonical” set of values for the functional representation. 相似文献
99.
Starting from Helmholtz's equation in inhomogeneous media, the associated radial second‐order equation is investigated through a Volterra integral equation. First the integral equation is considered in a sphere. Boundedness, uniqueness and existence of the (regular) solution are established and the series form of the solution is provided. An estimate is determined for the error arising when the series is truncated. Next the analogous problem is considered for a spherical layer. Again, boundedness, uniqueness and existence of two base solutions are established and error estimates are determined. The procedure proves more effective in the sphere. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
100.
Michele Conforti Gérard Cornuéjols Giacomo Zambelli 《Annals of Operations Research》2013,204(1):97-143
This survey is concerned with the size of perfect formulations for combinatorial optimization problems. By “perfect formulation”, we mean a system of linear inequalities that describes the convex hull of feasible solutions, viewed as vectors. Natural perfect formulations often have a number of inequalities that is exponential in the size of the data needed to describe the problem. Here we are particularly interested in situations where the addition of a polynomial number of extra variables allows a formulation with a polynomial number of inequalities. Such formulations are called “compact extended formulations”. We survey various tools for deriving and studying extended formulations, such as Fourier’s procedure for projection, Minkowski-Weyl’s theorem, Balas’ theorem for the union of polyhedra, Yannakakis’ theorem on the size of an extended formulation, dynamic programming, and variable discretization. For each tool that we introduce, we present one or several examples of how this tool is applied. In particular, we present compact extended formulations for several graph problems involving cuts, trees, cycles and matchings, and for the mixing set, and we present the proof of Fiorini, Massar, Pokutta, Tiwary and de Wolf of an exponential lower bound for the cut polytope. We also present Bienstock’s approximate compact extended formulation for the knapsack problem, Goemans’ result on the size of an extended formulation for the permutahedron, and the Faenza-Kaibel extended formulation for orbitopes. 相似文献