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991.
Spyridon Samothrakis Maria Fasli Diego Perez Simon Lucas 《Journal of Global Optimization》2017,67(4):893-907
Global optimisation of unknown noisy functions is a daunting task that appears in domains ranging from games to control problems to meta-parameter optimisation for machine learning. We show how to incorporate heuristics to Stochastic Simultaneous Optimistic Optimization (STOSOO), a global optimisation algorithm that has very weak requirements from the function. In our case, heuristics come in the form of Covariance Matrix Adaptation Evolution Strategy (CMA-ES). The new algorithm, termed Guided STOSOO (STOSOO-G), combines the ability of CMA-ES for fast local convergence (due to the algorithm following the “natural” gradient) and the global optimisation abilities of STOSOO. We compare all three algorithms in the “harder” parts of the Comparing Continuous Optimisers on Black-Box Optimization Benchmarking benchmark suite, which provides a default set of functions for testing. We show that our approach keeps the best of both worlds, i.e. the almost optimal exploration/exploitation of STOSOO with the local optimisation strength of CMA-ES. 相似文献
992.
Sonics and space are two topics which are not commonly considered together. However, sonic and ultrasonic models, devices and systems have space applications in both science and engineering, as well as showing promise in fields such as cleaning, healthcare and construction. This short paper describes some of these activities and appears as results start to come in from the Curiosity rover, which landed on Mars on the 6th of August, 2012, with over 20 piezoelectric and mechanically-resonant components on board. 相似文献
993.
Lucas W. Yeary Ji-Won Moon Claudia J. Rawn Lonnie J. LoveAdam J. Rondinone James R. Thompson Bryan C. ChakoumakosTommy J. Phelps 《Journal of magnetism and magnetic materials》2011,323(23):3043-3048
The magnetic properties of zinc ferrite (Zn-substituted magnetite, ZnyFe1-yFe2O4) formed by a microbial process compared favorably with chemically synthesized materials. A metal reducing bacterium, Thermoanaerobacter, strain TOR-39 was incubated with ZnxFe1−xOOH (x=0.01, 0.1, and 0.15) precursors and produced nanoparticulate zinc ferrites. Composition and crystalline structure of the resulting zinc ferrites were verified using X-ray fluorescence, X-ray diffraction, transmission electron microscopy, and neutron diffraction. The average composition from triplicates gave a value for y of 0.02, 0.23, and 0.30 with the greatest standard deviation of 0.02. Average crystallite sizes were determined to be 67, 49, and 25 nm, respectively. While crystallite size decreased with more Zn substitution, the lattice parameter and the unit cell volume showed a gradual increase in agreement with previous literature values. The magnetic properties were characterized using a superconducting quantum interference device magnetometer and were compared with values for the saturation magnetization (Ms) reported in the literature. The averaged Ms values for the triplicates with the largest amount of zinc (y=0.30) gave values of 100.1, 96.5, and 69.7 emu/g at temperatures of 5, 80, and 300 K, respectively indicating increased magnetic properties of the bacterially synthesized zinc ferrites. 相似文献
994.
995.
A gaussian memory function is used to compute the viscosity of dense fluid argon over a large region of states from the Lennard-Jones potential and the radial distribution function. The superposition approximation is used to evaluate the triplet correlation function and estimates of the errors introduced by this approximation are investigated. The agreement with experimental viscosities is quite satisfactory in the liquid region, but less so at lower densities and higher temperatures. The computed stress autocorrelation function exhibits those characteristics which are known from molecular dynamics studies. The stress autocorrelation remains monotonic even close to the triple point, where the same memory function leads to the well-known backscattering behaviour in the velocity autocorrelation function. This, too, is in agreement with the results of molecular dynamics. 相似文献
996.
997.
JO?O FIRMINO DA COSTA 《Pramana》2012,79(5):1215-1218
Results of searches for supersymmetry in events with significant missing transverse energy and two isolated leptons with the ATLAS experiment at the LHC are presented. Three analyses are presented here, the first two are analyses with leptons of opposite charge and same charge, respectively. The third one is an analysis that searches for an excess of same-flavour opposite-charge lepton pairs over those of different-flavour. Data corresponding to an integrated luminosity of 1 fb?1 are analysed. 相似文献
998.
999.
Costa Magno Barcelos de Souza Lucas Francisco Willian Mascaro Lucia Helena 《Journal of Solid State Electrochemistry》2018,22(5):1557-1562
Journal of Solid State Electrochemistry - Sb2Se3 (SSe) has been highlight as a low-cost, less complex, low toxicity, and earth-abundant photovoltaic (PV) absorber not only because of its excellent... 相似文献
1000.
Consider the iteration of an invertible matrix on the projective space: are the Morse components normally hyperbolic? As far as we know, this was only stablished when the matrix is diagonalizable over the complex numbers. In this article we prove that this is true in the far more general context of an arbitrary element of a semisimple Lie group acting on its generalized flag manifolds: the so called translations on flag manifolds. This context encompasses the iteration of an invertible non-diagonazible matrix on the real or complex projective space, the classical flag manifolds of real or complex nested subspaces and also symplectic grassmanians. Without these tools from Lie theory we do not know how to solve this problem even for the projective space. 相似文献