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941.
Steps towards the numerical simulation of the flow behind the slug front in horizontal slug flow performed with a streamfunction-vorticity representation of the mean flow and an energy dissipation model for the turbulence are discussed. The flow field consists of two vortices, one saddle point and four stagnation regions. Attention is focused on the following boundary conditions: moving wall jet, moving wall, free jet velocity discontinuity and vertical liquid-gas open surface. A dissipation flux boundary condition is suggested to simulate the interaction of the turbulent eddies with the open surface. A method to assess the necessity to use a transport model equation for the dissipation rather than a geometric specification of a length is suggested. Three different ways to characterize the mixing zone length are proposed. 相似文献
942.
The parallel algorithms of iterated defect correction methods (PIDeCM's) are constructed, which are of efficiency and high order B-convergence for general nonlinear stiff systems in ODE'S. As the basis of constructing and discussing PIDeCM's. a class of parallel one-leg methods is also investigated, which are of particular efficiency for linear systems. 相似文献
943.
In this paper we consider simple methods for the reconstruction of the Cauchy transform over a curve when an explicit parametrization of the latter is not provided. The methods consist of replacing the parametrization of the curve by piecewise polynomial interpolation followed by the use of Newton-Cotes type formulae for the integration. The order of convergence of the resulting quadrature is higher than would be expected on the basis of considerations involving just interpolation theory, provided that the Cauchy transform is evaluated at known nodes on the curve. These results allow the calculation of the Cauchy transform at other points with the same accuracy if this scheme is followed by an interpolatory formula of sufficiently high accuracy. 相似文献
944.
为了进一步深入理解掠入射驱动碰撞机制的特点与长处,以基频光正入射驱动为参照,用系列程序研究了6 mm和3 mm激光正入射驱动类镍银碰撞激发机制。在波长6 mm的激光正入射驱动下,激光能量直接沉积到增益区,大大提高了增益区的电子温度;以5 J驱动能量,获得有效增益系数为20.7 cm-1的高增益和有效增益长度积为41.4的深度饱和增益,与波长1.053 mm的正入射相比,以19%的驱动能量,使有效增益系数提高了60%。在波长3 mm的激光正入射驱动下,激光能量沉积到增益区附近,大大提高了增益区的电子温度;以15 J驱动能量,获得有效增益系数为21.2 cm-1的高增益和有效增益长度积为42.4的深度饱和增益,与波长1.053 mm的正入射相比,以57%的驱动能量,使有效增益系数提高64%。 相似文献
945.
K. E. Zoiros C. Botsiaris R. Chasioti C. S. Koukourlis 《Optical and Quantum Electronics》2007,39(14):1167-1181
The operation of an all-optical recirculating shift register implemented with the semiconductor optical amplifier (SOA)-based
ultrafast nonlinear interferometer (UNI) in a counter-propagating, inverting configuration is methodically studied and analyzed.
This is achieved by applying an appropriate model for a SOA deployed as the nonlinear element in an interferometric switch
driven by ultrafast and strong feedback optical pulses. By means of numerical simulation the impact of the critical functional
parameters on the formation of the switching window is thoroughly investigated and assessed enabling to provide useful design
rules for their proper selection and combination so as to optimize the specific metric and ensure high performance. The undertaken
theoretical treatment can be extended for characterizing other more complex all-optical circuits and subsystems of enhanced
functionality that employ this type of shift register as the key building module. 相似文献
946.
A powerful and efficient algorithm for numerical function optimization: artificial bee colony (ABC) algorithm 总被引:36,自引:0,他引:36
Swarm intelligence is a research branch that models the population of interacting agents or swarms that are able to self-organize.
An ant colony, a flock of birds or an immune system is a typical example of a swarm system. Bees’ swarming around their hive
is another example of swarm intelligence. Artificial Bee Colony (ABC) Algorithm is an optimization algorithm based on the
intelligent behaviour of honey bee swarm. In this work, ABC algorithm is used for optimizing multivariable functions and the
results produced by ABC, Genetic Algorithm (GA), Particle Swarm Algorithm (PSO) and Particle Swarm Inspired Evolutionary Algorithm
(PS-EA) have been compared. The results showed that ABC outperforms the other algorithms. 相似文献
947.
An efficient and versatile algebraic grid generation technique is presented for generating grid points in irregularly shaped and time-varying spatial domains. The method presented is based on the ‘two-boundary technique’ of Smith. The usefulness and the feasibility of the grid generation technique were demonstrated by (1) generating grid points inside one of the combustion chambers of a motored two-dimensional rotary engine and (2) obtaining numerical solutions for the flow field inside one of those combustion chambers. 相似文献
948.
The Holly-Preissmann two-point finite difference scheme (HP method) has been popularly used for solving the advection equation. The key idea of this scheme is to solve the dependent variable (i.e. the concentration for the pollutant transport problem) by the method of characteristics with the use of cubic interpolation on the spatial axis. The interpolating polynomials of higher order are constructed by use of the dependent variable and its derivatives at two adjacent grid points. In this paper a new interpolating technique is introduced for incorporation with the Holly-Preissmann two-point method. The new method is denoted herein as the Holly-Preissmann reach-back method (HPRB) and allows the characteristics to project back several time steps beyond the present time level. Through stability analyses it has been observed that the increase of the reach-back time step numbers for the characteristics indeed reduces the numerical damping and dispersive phenomena. A schematic model has been constructed to demonstrate the merits of this new technique for the calculation of the pure advection and dispersion equations. Numerical experiments and comparisons with analytical solutions which support and demonstrate this new technique are presented. 相似文献
949.
950.