含气率对PTS时压力容器内流动与传热的影响

本文对反应堆压力容器紧急安注时的流动与传热特性在1/10的模型上进行了流动可视化、局部传热系数以及混合函数的试验研究。针对三个热冲击敏感区域的部分测点,比较了环腔流速为0.5m/s、安注流速为1～30 m/s时不同含气率对下降环腔内流动与传热特性的影响,得出并分析了不同测点传热系数、混合函数的变化规律。研究结果表明:随着含气率增大,安注流体与环腔流体的混合增强;下降环腔内的含气率对小安注流速时的流动与传热影响显著,而对大安注流速时影响较小。     

On the Moments of Overflow and Freed Carried Traffic for the GI/M/C/0 System

In circuit-switched networks call streams are characterized by their mean and peakedness (two-moment method). The GI/M/C/0 system is used to model a single link, where the GI-stream is determined by fitting moments appropriately. For the moments of the overflow traffic of a GI/M/C/0 system there are efficient numerical algorithms available. However, for the moments of the freed carried traffic, defined as the moments of a virtual link of infinite capacity to which the process of calls accepted by the link (carried arrival process) is virtually directed and where the virtual calls get fresh exponential i.i.d. holding times, only complex numerical algorithms are available. This is the reason why the concept of the freed carried traffic is not used. The main result of this paper is a numerically stable and efficient algorithm for computing the moments of freed carried traffic, in particular an explicit formula for its peakedness. This result offers a unified handling of both overflow and carried traffics in networks. Furthermore, some refined characteristics for the overflow and freed carried streams are derived.     

准移动闭塞系统的元胞自动机模型及列车延迟传播规律的研究

在NaSch模型的基础上，针对铁路交通的特点提出一种用于模拟准移动闭塞系统的元胞自动机模型.应用该模型模拟了准移动闭塞系统列车延迟传播的交通现象，分析了准移动闭塞系统中的轨道定位单元长度、发车时间间隔、初始延迟时间等因素对列车延迟传播的影响. 关键词： 元胞自动机 交通流 准移动闭塞     

Microwave promoted energy-efficient N-formylation with aqueous formic acid

Microwave-induced organic reaction enhancement (‘MORE’) chemistry technique (open vessel; controlled microwave energy to stay below the boiling point of the reaction mixture) was used for the N-formylation of aliphatic and aromatic amines and amino heterocycles with aq formic acid (80%) on a multiple gram scale in a few minutes.     

Inequalities for the Moments and Distribution of the Ladder Height of a Random Walk

We obtain upper bounds for the tail distribution of the first nonnegative sum of a random walk and for the moments of the overshoot over an arbitrary nonnegative level if the expectation of jumps is positive and close to zero. In addition, we find an estimate for the expectation of the first ladder epoch.     

Equilibrium Shapes of Pressure Vessel Domes in Asymmetric Winding

Errors in the programs of winding pressure vessels can lead to an asymmetric reinforcement structure, which affects the equilibrium shape of their domes and the tension in the left and right families of filaments. In this paper, equations determining the equilibrium shape of the domes, the tension in filaments, and the shear stresses between layers are obtained. Examples with winding trajectories in the form of geodesics and constant-deviation lines are considered. It is found that, for pressure vessels, in the absence of external torque, the tension levels in filaments of the left and right families differ considerably. It is also revealed that, for actual friction coefficients in winding, the shear stresses taken up by the binder are insignificant. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 6, pp. 743–752, November–December, 2005.     

交通灯控制下城市主干道双车道多速元胞自动机交通流模型研究

提出一个城市主干道双车道多速元胞自动机交通流模型，此模型采用开放性 边界条件，在考虑诸多实际因素影响情况下，研究了主干道中车站的设置、交通灯绿信比对 车流量和车流速度的影响.计算机模拟所得到的基本图（流量 速度图）能较好地反映在交 通灯控制下城市主干道交通流真实状况. 关键词： 元胞自动机模型 交通流 主干道     

On the Existence of Solutions to Vector Quasivariational Inequalities and Quasicomplementarity Problems with Applications Break to Traffic Network Equilibria

For vector quasivariational inequalities involving multifunctions in topological vector spaces, an existence result is obtained without a monotonicity assumption and with a convergence assumption weaker than semicontinuity. A new type of quasivariational inequality is proposed. Applications to quasicomplementarity problems and traffic network equilibria are considered. In particular, definitions of weak and strong Wardrop equilibria are introduced for the case of multivalued cost functions.     

随机化交通灯的二维元胞自动机交通模型

元胞自动机交通模型以简单的规则反映交通系统中的多种因素，可以分析各种交通现象，且可在计算机上方便、高效地运作·Ｂｉｈａｍ－Ｍｉｄｄｌｅｔｏｎ－Ｌｅｖｉｎｅ模型（ＢＭＬ模型）实现了二维交通问题的元胞自动机模型的模拟研究·本文对ＢＭＬ模型作了改进，解除了该模型中关于交通灯同步变化的限制·在新模型中，每个路口的交通灯可以自由选定起始工作时间和变化节奏，于是可以更全面、准确地反映交通灯对交通系统性能的影响·本文还对新模型中出现的若干新效应作了解释·     

Formulation,Stability, and Computation of Traffic Network Equilibria as Projected Dynamical Systems

In this paper, we present a unified treatment and analysis of a dynamic traffic network model with elastic demands formulated and studied as a projected dynamical system. We propose a travel route choice adjustment process that satisfies the projected dynamical system. Under certain conditions, stability and asymptotical stability of the equilibrium patterns are then derived. Finally, two discrete-time algorithms, the Euler method and the Heun method, are proposed for the computation of the solutions, and convergence results established. The convergence results depend crucially on stability analysis. The performance of the algorithms is then illustrated on several transportation networks.