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排序方式: 共有121条查询结果,搜索用时 31 毫秒
51.
The main goal of this paper is to develop accuracy estimates for stochastic programming problems by employing stochastic approximation (SA) type algorithms. To this end we show that while running a Mirror Descent Stochastic Approximation procedure one can compute, with a small additional effort, lower and upper statistical bounds for the optimal objective value. We demonstrate that for a certain class of convex stochastic programs these bounds are comparable in quality with similar bounds computed by the sample average approximation method, while their computational cost is considerably smaller. 相似文献
52.
53.
N. D. Goletskiy B.Ya. Zilberman Yu. S. Fedorov I. V. Khonina D. N. Kukharev 《Czechoslovak Journal of Physics》2006,56(1):D509-D517
Comparative investigations were carried out to study the influence of TBP on Mo extraction by HDBP solutions in xylene and
TBP in xylene. The dependences of DMo on HNO3 concentration for both HDBP and D2EHPA have minima at about 3 mol/L HNO3. This shows similar extraction properties of HDBP and D2EHPA. The presence of TBP in the solvent results in the reduction
of Mo extraction and in an increase in the formal slopes of the falling and rising parts of the logDMo — log[HNO3] curve from −0.5 and +2 up to −2 and +4.
Solvent loading curves with Mo show that in the absence of TBP a molybdenum solvate with two molecules of HDBP is formed at
low acidity. Anomalous increase in the maximum solvent loading in the presence of TBP is caused by the ability of TBP to extract
Mo from oversaturated low acidity solutions following the acidic mechanism. A molybdenum solvate with two HDBP molecules and
one HNO3 molecule is possibly formed at high acidity.
A flowsheet for Mo recovery from HLW with HDBP-TBP solvent was tested in centrifugal contactors. 相似文献
54.
V. G. Maiorov A. I. Nikolaev B. Ya. Zilberman 《Russian Journal of Applied Chemistry》2007,80(1):152-154
Extraction, washing, back extraction, and precipitation of Th(IV) from the backwash in the hydrochloric acid processing of perovskite are studied. Process conditions are optimized to obtain a concentrate with a ThO2 content of about 85 wt %. 相似文献
55.
Maisels Arkadi Jordan Frank Einar Kruis Frank Fissan Heinz 《Journal of nanoparticle research》2003,5(3-4):225-235
A Direct Simulation Monte Carlo (DSMC) technique is applied for describing the dynamics of aerosol charging. The method is based on the transformation of known combination coefficients into charging probabilities. Changes in the particle charge distribution are computed as a stochastic game, calculating the time-step after each event. The simulations are validated by comparison with analytical solutions for unipolar aerosol diffusion charging and aerosol photocharging. The advantage of the DSMC method lies in the uncomplicated simulation of multi-dimensional systems that would result in very elaborate population balances. The DSMC method is used for simulation of the photocharging of moderately concentrated bicomponent polydisperse aerosols. By means of this method, the influence of the particle parameters (size, material) on the dynamics of the charge distribution in different size and material fractions has been studied. It is shown that charge separation between size or material fractions can be achieved for aerosol components with dissimilar work functions, while the total aerosol charge is zero. 相似文献
56.
Arkadi Berezovski Jüri Engelbrecht Gérard A. Maugin 《Archive of Applied Mechanics (Ingenieur Archiv)》2011,81(2):229-240
The formal structure of generalized continuum theories is recovered by means of the extension of canonical thermomechanics
with dual weakly non-local internal variables. The canonical thermomechanics provides the best framework for such generalization.
The Cosserat, micromorphic, and second gradient elasticity theory are considered as examples of the obtained formalization. 相似文献
57.
Thibault J.-Y. Derrien Jörg Krüger Tatiana E. Itina Sandra Höhm Arkadi Rosenfeld Jörn Bonse 《Applied Physics A: Materials Science & Processing》2014,117(1):77-81
The formation of laser-induced periodic surface structures (LIPSS, ripples) upon irradiation of silicon with multiple irradiation sequences consisting of femtosecond laser pulse pairs (pulse duration 150 fs, central wavelength 800 nm) is studied numerically using a rate equation system along with a two-temperature model accounting for one- and two-photon absorption and subsequent carrier diffusion and Auger recombination processes. The temporal delay between the individual equal-energy fs-laser pulses was varied between 0 and ~4 ps for quantification of the transient carrier densities in the conduction band of the laser-excited silicon. The results of the numerical analysis reveal the importance of carrier generation and relaxation processes in fs-LIPSS formation on silicon and quantitatively explain the two time constants of the delay-dependent decrease of the low spatial frequency LIPSS (LSFL) area observed experimentally. The role of carrier generation, diffusion and recombination is quantified individually. 相似文献
58.
Yu. V. Gulyaev P. E. Zilberman E. M. Epshtein 《Journal of Experimental and Theoretical Physics》2012,114(2):296-304
The effect of spin-polarized current on the steady-state magnetization and oscillations of antiferromagnet magnetization in
a ferromagnetic-antiferromagnetic magnetic junction is analyzed. The macrospin approximation is generalized to describe antiferromagnets.
The canted configuration of the antiferromagnet and the resultant magnetic moment are produced by the application of an external
magnetic field. The resonance frequency, damping, and threshold current density corresponding to the emergence of instability
are calculated. The possibility of generating weakly damped magnetization oscillations in the terahertz range is demonstrated.
The effect of fluctuations on the canted configuration of the antiferromagnet is discussed. 相似文献
59.
Peter Ván Arkadi Berezovski Christina Papenfuss 《Continuum Mechanics and Thermodynamics》2014,26(3):403-420
Governing equations of dissipative generalized solid mechanics are derived by thermodynamic methods in the Piola–Kirchhoff framework using the Liu procedure. The isotropic small-strain case is investigated in more detail. The connection to the Ginzburg–Landau type evolution, dual internal variables, and a thermodynamic generalization of the standard linear solid model of rheology is demonstrated. Specific examples are chosen to emphasize experimental confirmations and predictions beyond less general approaches. 相似文献
60.
Bruce Cox Anatoli Juditsky Arkadi Nemirovski 《Journal of Optimization Theory and Applications》2017,172(2):402-435
The majority of first-order methods for large-scale convex–concave saddle point problems and variational inequalities with monotone operators are proximal algorithms. To make such an algorithm practical, the problem’s domain should be proximal-friendly—admit a strongly convex function with easy to minimize linear perturbations. As a by-product, this domain admits a computationally cheap linear minimization oracle (LMO) capable to minimize linear forms. There are, however, important situations where a cheap LMO indeed is available, but the problem domain is not proximal-friendly, which motivates search for algorithms based solely on LMO. For smooth convex minimization, there exists a classical algorithm using LMO—conditional gradient. In contrast, known to us similar techniques for other problems with convex structure (nonsmooth convex minimization, convex–concave saddle point problems, even as simple as bilinear ones, and variational inequalities with monotone operators, even as simple as affine) are quite recent and utilize common approach based on Fenchel-type representations of the associated objectives/vector fields. The goal of this paper was to develop alternative (and seemingly much simpler) decomposition techniques based on LMO for bilinear saddle point problems and for variational inequalities with affine monotone operators. 相似文献