多孔介质BISQ模型中的慢纵波

着重研究了多孔介质BISQ模型中慢纵波的基本特性.给出了BISQ模型下慢纵波速度 和衰减的低频近似公式.与Biot理论对比，BISQ模型中慢纵波的衰减随频率降低急剧增大， 且随喷射流长度的减小而增加；相速度随喷射流长度的减小而增加，其低频极限值不是零； 孔隙流体位移与固相骨架位移之比的幅值随喷射流长度的增加而减小，其相位特点与Biot模 型预测的不同；在流体与孔隙介质的边界上可产生更大的渗流.为对比，同时也给出快纵波 的行为.依据BISQ模型可推断：非黏滞流体饱和孔隙介质中不存在喷射流机理；BISQ模型中 关键词： 多孔介质 喷射流 慢纵波 动力协调     

基于径向基函数神经网络的Lorenz混沌系统滑模控制

针对受参数不确定和外扰影响的混沌Lorenz系统，提出一种基于径向基函数（RBF）神经网 络的滑模控制方法.基于被控系统在不稳定平衡点处状态误差的可控规范形，设计滑模切换 面并将其作为神经网络的唯一输入.单入单出形式的RBF控制器隐层只需7个径向基函数，网 络的权值则依滑模趋近条件在线确定.仿真表明该控制器对系统参数突变和外部干扰具有鲁棒性，同时抑制了抖振. 关键词： 混沌控制 滑模 径向基函数神经网络 Lorenz系统     

Piecewise Deterministic Markov Control Processes with Feedback Controls and Unbounded Costs

The control of piecewise-deterministic processes is studied where only local boundedness of the data is assumed. Moreover the discount rate may be zero. The value function is shown to be solution to the Bellman equation in a weak sense; however the solution concept is strong enough to generate optimal policies. Continuity and compactness conditions are given for the existence of nonrelaxed optimal feedback controls.     

Dynamic boundary stabilization of a Reissner–Mindlin plate with Timoshenko beam

This paper is concerned with well‐posedness results for a mathematical model for the transversal vibrations of a two‐dimensional hybrid elastic structure consisting of a rectangular Reissner–Mindlin plate with a Timoshenko beam attached to its free edge. The model incorporates linear dynamic feedback controls along the interface between the plate and the beam. Classical semigroup methods are employed to show the unique solvability of the coupled initial‐boundary‐value problem. We also show that the energy associated with the system exhibits the property of strong stability. Copyright © 2004 John Wiley & Sons, Ltd.     

Thermodynamic study of sodium-iron oxides: Part II. Ternary phase diagram of the Na-Fe-O system

Studies on ternary phase diagrams of the Na-Fe-O system have been carried out from the thermodynamic point of view. Thermodynamic data of main ternary Na-Fe oxides Na₄FeO₃(s), Na₃FeO₃(s), Na₅FeO₄(s) and Na₈Fe₂O₇(s) have been assessed. A user database has been created by reviewing literature data together with recent DSC and vapor pressure measurements by the present authors. New ternary phase diagrams of the Na-Fe-O system have been constructed from room temperature to 1000 K. Stable conditions of the ternary oxides at 800 K were presented in predominance diagram as functions of oxygen pressure and sodium pressure.     

微全分析系统检测方法的研究进展

综述了不同类型的检测方法在微全分析系统的应用，并简述了各类型的检测方法的优缺点。引用文献92篇。     

Political and economic rationality leads to velcro bifurcation

In this paper political and economic rationality is modelled regarding an economic problem with a four-dimensional dynamical system taking into consideration the information about the problem spread among the people who support the political alternatives. Under special parameter conditions velcro bifurcation occurs, which destabilizes the equilibrium points when information is going to spread. The last stable equilibrium point is related to the economically rational equilibrium point.     

Stability Conditions of the MMAP [ K ]/ G [ K ]/1/ LCFS Preemptive Repeat Queue

In this paper, we study the stability conditions of the MMAP[K]/G[K]/1/LCFS preemptive repeat queue. We introduce an embedded Markov chain of matrix M/G/1 type with a tree structure and identify conditions for the Markov chain to be ergodic. First, we present three conventional methods for the stability problem of the queueing system of interest. These methods are either computationally demanding or do not provide accurate information for system stability. Then we introduce a novel approach that develops two linear programs whose solutions provide sufficient conditions for stability or instability of the queueing system. The new approach is numerically efficient. The advantages and disadvantages of the methods introduced in this paper are analyzed both theoretically and numerically.     

统一混沌系统的控制

对统一混沌系统建立了自反馈控制、错位反馈控制和自适应控制方法，在理论上给予严格证明，数值仿真表明这些方法是很有效的.还纠正了文献［１０］的某些不足. 关键词： 统一混沌系统 反馈 自适应 控制 Routh-Hurwitz定理     

Birkhoff系统的Hojman定理的几何基础

研究了Birkhoff系统的Hojman定理的几何基础.建立了系统的运动微分方程和Hojman守恒 定理，利用现代微分几何给出了Birkhoff系统的Hojman定理的一个证明. 关键词： Birkhoff系统 Hojman定理 对称性 微分几何