LATTICE BGK MODEL FOR THE INCOMPRESSIBLE NAVIER-STOKES EQUATION

1 .　INTRODUCTIONInthelastdecadeorso ,theLatticeBoltz mann (LB)methodhasemergedasanewandef fectivenumericaltechniqueofComputationalFluidDynamics (CFD) [1 3] ,especially ,theLBGKmodelhasachieved greatsuccessinsimulationsoffluidflowsandinmodeling physicsinfluids[4 9] .ButLBGKmodelshouldbeviewedasanarticicialcompressibleschemetosimulateincompressiblefluid[10 ] .Inotherwords,throughmultiscalingex pansionandChapman Enskog procedure[11] ,thecompressibleNavier Stokesequationscanberecov …     

A class of multipartner matching markets with a strong lattice structure

Summary. For a two-sided multipartner matching model where agents are given by path-independent choice functions and no quota restrictions, Blair [7] had shown that stable matchings always exist and form a lattice. However, the lattice operations were not simple and not distributive. Recently Alkan [3] showed that if one introduces quotas together with a monotonicity condition then the set of stable matchings is a distributive lattice under a natural definition of supremum and infimum for matchings. In this study we show that the quota restriction can be removed and replaced by a more general condition named cardinal monotonicity and all the structural properties derived in [3] still hold. In particular, although there are no exogenous quotas in the model there is endogenously a sort of quota; more precisely, each agent has the same number of partners in every stable matching. Stable matchings also have the polarity property (supremum with respect to one side is identical to infimum with respect to the other side) and a property we call {\it complementarity}. Received: May 5, 2000; revised version: January 25, 2001     

A LATTICE BOLTZMANN MODELING FOR THE WESTERN BOUNDARY CURRENT IN A LINEAR WIND-DRIVEN QUASI-GEOSTROPHIC MODEL

1 .　INTRODUCTIONLatticeBoltzmannMethod (LBM )isanewnumericalmethodforcomputationalfluid (ChenandDoolen 1998) ,whichisdevelopedfromLat ticeGasCellularAutomaton (LGCA )inthelate80satlastcentury .LBMusesthecontinuousdistri butionfunctiontoreplacetheBooleanvariablesusedinLGCA .Asaresult ,LBMovercomesmanyshortcomingsofitsancestor ,suchasnoise ,notconformingtoGalileoinvarianceetc .HeandLuo(1997)developedLBMasaself containedsystemconstructedtheamodelwithoutconnectiontoLGCA .LBMha…     

Endogenous time preference and optimal growth

We adapt the classic one-sector optimal growth model to include an endogenous rate of time preference along the lines of Becker and Mulligan (1997). The resulting model is both time-consistent and analytically tractable. Capital sequences are shown to be globally monotone and stable under very general circumstances using lattice programming techniques and value orders. We analyze a series of examples that exhibit a variety of behaviors, including closed-form solutions, unique steady-states, multiple steady-states, and conditionally sustained growth. The endogenous rate of discount preserves monotonicity and stability while allowing for the possibility of non-global convergence.I would like to thank Robert Becker, Leonard Mirman, Michael Kaganovich, Itzhak Zilcha, and an anonymous referee for helpful comments and discussions.     

The vector lattice structure of the n-person TU games

We show that any cooperative TU game is the maximum of a finite collection of a specific class of the convex games: the almost positive games. These games have non-negative dividends for all coalitions of at least two players. As a consequence of the above result we show that the class of modular games is a set of generators of the distributive lattice of all cooperative TU games. Finally, we characterize zero-monotonic games using a strong max-convex decomposition.     

扁球体泥沙颗粒沉降的三维格子Boltzmann模型

应用格子Boltzmann方法(Lattice Boltzmann Method,LBM)模拟扁球体单颗粒沉降,并引入大涡模拟(Large Eddy Simulation,LES)描述较大颗粒沉降引起的尾流紊动,建立了扁球状泥沙颗粒沉降的三维数值模型。利用该模型对不同雷诺数下(1～7 580)扁球体泥沙颗粒的静水沉降进行了验证模拟。数值模拟结果与已有试验数据相比较,在泥沙颗粒沉降轨迹、沉降速度和阻力系数等方面有较好的一致性。     

SIMULATION OF SOLUTE TRANSPORT IN A PARALLEL SINGLE FRACTURE WITH LBM/MMP MIXED METHOD

This article deals with the solute transport in a single fracture with the combination of the Lattice Boltzmann Method （LBM） and Modified Moment Propagation （MMP） method, and this mixed method is proved to have several advantages over the LBM and Moment Propagation （MP） mixed method which leads to negative concentrations under some conditions in computation. The disadvantage of LBM/MP has been overcome to a certain extent. Also, this work presents an LBM solution of modeling single fractures with uniformly or randomly distributed grains, which can provide a new path of applying the LBM in solute transport simulation in fractures.     

黏性泥沙不等速沉降絮凝的格子Boltzmann模拟

建立黏性泥沙运动的三维格子Boltzmann模型,对黏性泥沙不等速沉降絮凝过程进行全尺度直接数值模拟,从微观角度分析了泥沙颗粒不等速沉降形成的絮团特性和絮团成长过程。模拟结果与已有实验结果一致。模拟结果还表明,不等速沉降时不同泥沙浓度条件下形成的絮团若大小相近则沉降速度接近,但泥沙浓度对水体中泥沙总体平均沉速有明显影响,泥沙浓度越高,泥沙平均沉速越大,主要是因为泥沙浓度越大,颗粒之间越容易发生碰撞而形成更大、更多的絮团。     

三峡电站厂房屋盖采用网架结构的研究

三峡电站厂房屋盖采用空间网架结构，具有整体稳定好，刚度高，经济指标好等优点，在网架选型上，经比较，推荐正放四角锥，两边起坡网架形式，网架支承方式，采用“上、下弦铰支”可显著提高厂房的整体刚度。     

创新网络治理机制与绩效：基于灰格序方法的创新联盟实证分析

对创新网络治理机制进行了系统的理论梳理,对创新网络治理机制、形成机制、整合机制、创新机制与治理绩效进行了构念解释,并建立了绩效测量指标。应用熵值法确定指标权重,结合灰色关联法与格序决策法,提出了灰格序评价方法。通过江苏省产业技术创新战略联盟实证研究,发现治理机制对创新网络治理绩效的作用具有较为显著的周期性特点。其中,形成机制具有先导性,是整合机制与创新机制发生作用的前提,创新机制具有滞后性,必须建立在有效的形成与整合机制的基础之上。