考虑边流量有限的网络路径博弈问题研究

考虑每条边有流量约束的网络路径博弈问题, 根据收益函数单调递增的特点分析其内在零和性质, 并建模为存在公共边的路径博弈模型。在寻找均衡解的过程中, 首先考虑非合作的情形, 在局中人风险中性的假设下, 给出了求Nash均衡流量分配的标号法并证明该均衡分配的唯一性。接着进一步考虑局中人合作的可能性, 给出模型求得所有局中人的整体最大收益, 并基于纳什谈判模型给出目标函数为凸函数的数学模型确定唯一收益分配方案。事实上, 该方案是对剩余价值的平均分配。最后给出一个算例, 验证本文理论和方法的可行性。关键词:流量约束; 均衡流量; 网络路径博弈; 收益分配     

微流量输液泵

对近几年出现的以声、光、电、磁、热等为基本激发形式的新颖的微流量输液泵的原理、特点作了评述。     

通道宽度对二维粗糙边界斜面颗粒流的影响

在此之前已经报道了二维斜面颗粒流在通道中的分布规律以及二维斜面粗糙边界附近的颗粒 流量密度（ξ=ρ·ν）分布.本文则主要研究通道宽度W对边界附近颗粒流量密度(ξ=ρ· ν)分布的影响.结果表明，颗粒流量密度随通道宽度的变化（ξ W）存在一临界通道宽度W c.在本实验条件下临界通道宽度Wc=70d.当通道宽度小于临界宽度Wc时 ，通道中距边界20d—30d区间内的相对颗粒流量密度随斜面倾斜角的变化可描述为ξ∝( sinθ)α，α是与通道宽度W有关的参数，其数值在032至085之间. 关键词： 二维颗粒流 颗粒物质 颗粒流量密度     

Continuum modeling for two-lane traffic flow

In this paper, we study the continuum modeling of traffic dynamics for two-lane freeways. A new dynamics model is proposed, which contains the speed gradient-based momentum equations derived from a car-following theory suited to two-lane traffic flow. The conditions for securing the linear stability of the new model are presented. Numerical tests are carried out and some nonequilibrium phenomena are observed, such as small disturbance instability, stop-and-go waves, local clusters and phase transition. The project supported by the National Natural Science Foundation of China (70521001) The English text was polished by Yunming Chen.     

空中交通流量管理中的改航策略研究

针对在恶劣天气下出现的大规模航班延误情况,根据机场和航路段的动态容量约束,建立了改航策略模型,并提出求解该模型的有效算法.选择全国航班时刻表进行仿真,仿真结果表明:该模型提供了在恶劣天气下更安全、更经济的航班改航策略,可为战术级流量管理提供辅助决策.     

最优数学模型筛选法确定流量系数的经验公式

应用简单的最小二乘回归分析原理对多个数学模型进行分析,得到了水利工程中有坎宽顶堰流量系数的经验公式,并对其精度进行了讨论.对指导实际工程意义重大.     

MULTISCALE OPTIMIZATION OF FLOW DISTRIBUTION BY CONSTRUCTAL APPROACH

Constructal approach is a recent concept allowing to generate and optimize multi-scale structures, in particular, branching structures, connecting a microscopic world to a macroscopic one, from an engineer＇s point of view. Branching morphologies are found in many types of natural phenomena, and may be associated to some kind of optimization, expressing the evolutionary adaptation of natural systems to their environment, In a sense, the constructal approach tries to imitate this morphogenesis while short-cutting the trial-and-error of nature. The basic ideas underlying the constructal concept and methodology are illustrated here by the examples of fluid distribution to a multi-channel reactor, and of the design of a porous material and system for gas adsorption and storage. In usual constructal theory, a tree branching is postulated for the channels or flow-paths or conductors, usually a dichotomic tree （every branch is divided into two ＂daughters＂）. The objective function of the optimization is built from the resistances to mass or heat transport, expressed here as ＂characteristic transport times＂, and the geometric result is expressed as a shape factor of a domain. The optimized shape expresses the compromise between the mass or heat transport characteristics at adjacent scales. Under suitable assumptions, simple analytical scaling laws are found, which relate the geometric and transport properties of different scales. Some challenging geometric problems may arise when applying the constructal approach to practical situations where strong geometric constraints exist. The search for analytical solutions imposes simplifying assumptions which may be at fault, calling for less constraining approaches, for example making only weak assumptions on the branching structure. Some of these challenges are brought forward along this text.     

氢气流量对混合物理化学气相沉积法制备MgB_2超薄膜的影响

用混合物理化学气相沉积法(Hybrid physical-chemical vapor deposition简称为HPCVD)制备了MgB2超薄膜.在背景气体压强、B2H6的流量和成膜时间等条件一定的情况下,当氢气的流量从200到400sccm范围内变化时,观察了其对成膜的影响.结果显示,随氢气流量增大,膜表面粗糙度增大,同时膜面的连接性变好,伴随着样品的超导转变温度得到提高.对于平均厚度是10nm和15nm的样品,氢气流量分别是200sccm和300sccm时,Tc分别是26K和33K与28K和37K.     

基于换乘行为的轨道交通网络模型研究

换乘行为是保持轨道交通网络正常运行的关键因素.针对轨道交通网络,提出一种添加换乘因素的网络模型构造方法.首先,根据换乘站点的交汇线路数量N,再裂变出N-1个换乘站点;其次,这N个换乘站点相互之间有换乘通道相连,且每条线路通过其中一个换乘站点;最后将构造方法运用到北京轨道交通网络,并通过仿真实验对比分析新旧网络模型的基本参数.结果表明:新建轨道交通网络模型在换乘流量的确定、负荷平均最短出行时间等方面弥补了以往模型的不足.     

求解二次分配问题的新的流量模型

二次分配问题是具有广泛应用背景的经典组合优化难题之一。本文在二次分配问题已有线性化模型的基础上,提出了一种新的基于流量的线性化模型。数值试验结果表明,新模型无论从时间上还是计算节点数都更具有优势。