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961.
Hans Weber 《Ricerche di matematica》2009,58(1):15-32
We study decomposition theorems for modular functions on lattices and the relationship between such decompositions and lattice
properties of a suitable system of uniformities. We give a purely topological characterization for the validity of a decomposition
theorem of a certain type and examine when this topological condition is satisfied, namely when a system of lattice uniformities
is a Boolean algebra consisting of permutable uniformities.
相似文献
962.
In this paper, a new lattice Boltzmann equation which is independent of time is proposed. Based on the new lattice Boltzmann equation, some steady problems can be modeled by the lattice Boltzmann method. In the further study, the Laplace equation is investigated with the method of the higher-order moment of equilibrium distribution functions and a series of partial differential equations in different space scales. The numerical results show that the new method is effective. 相似文献
963.
Marni Mishna 《Journal of Combinatorial Theory, Series A》2009,116(2):460-477
This work considers the nature of generating functions of random lattice walks restricted to the first quadrant. In particular, we find combinatorial criteria to decide if related series are algebraic, transcendental holonomic or otherwise. Complete results for walks taking their steps in a maximum of three directions of restricted amplitude are given, as is a well-supported conjecture for all walks with steps taken from a subset of 2{0,±1}. New enumerative results are presented for several classes, each obtained with a variant of the kernel method. 相似文献
964.
Let Var(M
plan) denote the variety generated by the class M
plan of planar modular lattices. In 1977, based on his structural investigations, R. Freese proved that Var(M
plan) has continuumly many subvarieties. The present paper provides a new approach to this result utilizing lattice identities.
We also show that each subvariety of Var(M
plan) is generated by its planar (subdirectly irreducible) members.
Dedicated to the memory of András P. Huhn
This research was partially supported by the NFSR of Hungary (OTKA), grant no. T 049433, T 48809 and K 60148. 相似文献
965.
Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electrochemical systems requires powerful numerical tools. Over the past decades, the lattice Boltzmann(LB) method has attracted broad interest in the computational fluid dynamics and the numerical heat transfer communities, primarily due to its kinetic nature making it appropriate for modeling complex multiphase transport phenomena. More importantly, the LB method fits well with parallel computing due to its locality feature, which is required for large-scale engineering applications. In this article, we review the LB method for gas–liquid two-phase flows, coupled fluid flow and mass transport in porous media, and particulate flows. Examples of applications are provided in fuel cells and flow batteries. Further developments of the LB method are also outlined. 相似文献
966.
《Particuology》2017
A two-dimensional coupled lattice Boltzmann immersed boundary discrete element method is introduced for the simulation of polygonal particles moving in incompressible viscous fluids. A collision model of polygonal particles is used in the discrete element method. Instead of a collision model of circular particles, the collision model used in our method can deal with particles of more complex shape and efficiently simulate the effects of shape on particle–particle and particle–wall interactions. For two particles falling under gravity, because of the edges and corners, different collision patterns for circular and polygonal particles are found in our simulations. The complex vortexes generated near the corners of polygonal particles affect the flow field and lead to a difference in particle motions between circular and polygonal particles. For multiple particles falling under gravity, the polygonal particles easily become stuck owing to their corners and edges, while circular particles slip along contact areas. The present method provides an efficient approach for understanding the effects of particle shape on the dynamics of non-circular particles in fluids. 相似文献
967.
Introduction Raman scattering is a powerful nondestructive technique that gives vibrational information about organic and inorganic materials. Raman scattering features, such as intensity, frequency and width, are strongly dependent on compositions, defects, short-range orders, crystal structures, and internal stresses of materials. Therefore, it has been widely used to obtain detailed information about the structural properties of semiconductors, high-Tc superconductors, ceramics, catalysts, carbon based materials, and Ⅲ-Ⅴ valent metallic nitride materials, including lattice perfection, strain, crystalline, interface, and compositional uniformity[1]. 相似文献
968.
A.Deur 《中国物理C(英文版)》2009,33(12)
We present recent results from Jefferson Lab on sum rules related to the spin structure of the nucleon. We then discuss how the Bjorken sum rule with its connection to the Gerasimov-Drell-Hearn sum, allows us to conveniently define an effective coupling for the strong force at all distances. 相似文献
969.
The lattice Boltzmann method (LBM) has gained increasing popularity in the last two decades as an alternative numerical approach for solving fluid flow problems. One of the most active research areas in the LBM is its application in particle-fluid systems, where the advantage of the LBM in efficiency and parallel scalability has made it superior to many other direct numerical simulation (DNS) techniques. This article intends to provide a brief review of the application of the LBM in particle-fluid systems. The numerical techniques in the LBM pertaining to simulations of particles are discussed, with emphasis on the advanced treatment for boundary conditions on the particle-fluid interface. Other numerical issues, such as the effect of the internal fluid, are also briefly described. Additionally, recent efforts in using the LBM to obtain closures for particle-fluid drag force are also reviewed. 相似文献
970.
The thermal creeping effect on slip velocity of air forced convection through a nanochannel is studied for the first time by using a lattice Boltzmann method. The nanochannel side walls are kept hot while the cold inlet air streams along them. The computations are presented for the wide range of Reynolds number, Knudsen number and Eckert number while slip velocity and temperature jump effects are involved. Moreover appropriate validations are performed versus previous works concerned the micro–nanoflows.The achieved results are shown as the velocity and temperature profiles at different cross sections, streamlines and isotherms and also the values of slip velocity and temperature jump along the nanochannel walls. The ability of the lattice Boltzmann method to simulate the thermal creeping effects on hydrodynamic and thermal domains of flow is shown at this study; so that its effects should be involved at lower values of Eckert number and higher values of Reynolds number especially at entrance region where the most temperature gradient exists. 相似文献