交通网络中动态OD矩阵反推算法研究

文章根据极大熵基本原理并运用排列组合理论推导出OD矩阵反推的极大熵模型;然后用拉格朗日乘子法求得该模型的非线性方程组,并运用Newton算法对此非线性方程组求解,得到动态OD估计矩阵。最后,在实例应用中,应用此模型和文章给出的模型解法取得了令人满意的结果。     

二维随机变量的分布函数

概率论与数理统计是学习现代科学技术的重要理论基础,同时它也是考研必考科目之一,在教学过程中,我遇到了这样一道题目,本文由这道概率习题联想到了几个问题:二维随机变量的分布函数是否唯一;三元三次方程组解的唯一性.     

基于非线性动力学的八类运动想象脑电信号特征提取方法研究

对多类运动想象的脑电信号进行特征提取是脑机接口的关键技术之一,很多研究表明大脑是一个非线性动力学系统[1]。本文采用非线性动力学的Lyapunov指数、相关维数、近似熵对八类运动想象脑电信号进行特征提取,并分析了其提取效果,得出近似熵算法对脑电信号进行特征提取时效果最好。最后确定了近似熵算法最优参数,为之后的脑电信号特征提取工作提供了依据。     

一个生态模型周期解的存在性

文章采用更精确的先验估计,利用重合度理论讨论了一类与厌氧消化过程微生物生态模型有关的微分方程组,得到了该方程组存在2周期解的充分条件,改进了相关文献中的定理。     

风水引射器三位一体综合治理技术的研究应用

本文分析了回采工作面上隅角有害气体积聚的原因以及目前解决这一问题的方法和存在问题;对其研制的风水引射器系统的应用效果进行了考察,肯定了该系统在生产中应用的有效性。     

企业持续竞争优势的熵变模型与预警机制研究

熵是企业竞争优势发展演化的内在动力。正熵的产生使竞争优势减退,负熵的产生使竞争优势增强,正熵和负熵的交互作用使得竞争优势呈现周期动态变化,当总熵值高于行业平均熵值时,企业系统运行进入警戒区,这时候,需要进行变革,引入负熵,使总熵值小于零,最终实现企业的持续竞争优势。     

高熵合金的制备方法及研究

高熵合金亦被叫作多组元高熵合金,其是由5种以上金属元素组成的高熵值得合金,并且其组成元素分布均匀。高熵合金近些年来应用广泛,因为其在强度、硬度、腐蚀性能和电阻率上皆优于传统合金材料,在航空航天等领域的应用前景极为兴盛,在金属材料领域的研究方面也在潜移默化的发展。本文对近年来关于高熵合金的制备方法,就其基于固相、液相、气相的成形制备方法进行系统的介绍,最后指出了现今高熵合金还需改善的问题并对未来的研究方向进行瞻望。     

经济能·经济熵·经济危机

社会经济运行经常出现紊乱现象的根本原因是什么?本文把物理学中能和熵的概念引入到经济研究中来,提出了经济能、经济熵、经济熵率等概念,以此为基础提出了熵经济危机理论。本文认为市场经济是产生熵经济危机的社会条件,科学技术是产生熵经济危机的技术条件和物质基础。熵经济危机是一种必然的社会经济现象。     

基于熵权和TOPSIS结合的企业运营能力综合评价

本文提出基于熵权系数与TOPSIS集成的企业运营能力评价方法,避免了传统评价方法中主观性强等弊端,并且使用该方法进行算法示例,详细说明各个计算步骤,先通过熵计算出评价权值,再将其应用于理想法（TOPSIS）集成,确定出接近理想解的最优值,不仅具有实际意义且更具科学性。     

经济动力学方程的对称群分析

在描述经济演化行为的各种理论和方法中,经济动力学以及相应的经济动力学方程体系是一种有力的工具。通过计算机数值模拟来分析系统的演化行为,但对于系统偏离均衡位置后的变化方式以及系统从一个均衡(定态解)向另一个均衡转移的非平衡路径等问题还未得到圆满的解决。 越来越多的经济学家开始相信,在复杂、多变量的经济系统背后,存在着一个少维的动力学机制,决定着系统的发展和演化。由于这样的机制的存在,使得千差万别的具体经济系统的演化可能具有某些在变换下保持不变的共性,即对称性。一个具有某种内在的动力学机制,用微分动力学方程描述的系统的对称性,是系统内在机制在方程形式上的反映,系统所具有的对称性的种类和数目中隐含着系统演化方式之间的相互联系。     

Multiple solutions in systems of functional differential equations

This paper proposes conditions for the existence and uniqueness of solutions to systems of linear differential or algebraic equations with delays or advances, in which some variables may be non-predetermined. These conditions represent the counterpart to the Blanchard and Kahn conditions for the functional equations under consideration. To illustrate the mathematical results, applications to an overlapping generations model and a time-to-build model are developed.     

The forward method as a solution refinement in rational expectations models

This paper generalizes the standard forward method of recursive substitution to a general class of linear rational expectations models with potentially multiple fundamental solutions. It is shown that the existence and uniqueness of the well-known forward solution are preserved in a general context. We also propose a key property embedded in the forward solution - the no-bubble condition - as an economically sensible solution refinement in the class of fundamental solutions. In the literature, the no-bubble condition has been assumed to rule out non-fundamental bubble solutions. We show that the forward solution is the only rational expectations equilibrium satisfying the no-bubble condition and consequently, it is the most relevant fundamental solution within the class of fundamental equilibria. Several economic examples are provided where the fundamental solutions obtained by other solution methods and refined by other solution selection criteria violate the no-bubble condition.     

Generalized extreme value discrete choice demand models : Existence and uniqueness of market equilibria

Generalized extreme value (GEV) random utility choice models have been suggested as a development of the multinomial logit models that allows the random components of various alternatives to be statistically dependent. This paper establishes the existence of and provides necessary and sufficient uniqueness conditions for the solutions to a set of equations that may be interpreted as an equilibrium of an economy, the demand side of which is described by a multiple-segment GEV random choice model. The same equations may alternatively be interpreted in a maximum likelihood estimation context. The method employed is based on optimization theory and may provide a useful computational approach. The uniqueness results suggest a way to introduce segregation/integration effects into logit type choice models. Generalization to non-GEV models are touched upon.     

一类非单调二元算子方程解的存在唯一性

利用锥理论和非对称迭代方法,讨论了一类非单调二元算子方程解的存在唯一性,给出了迭代序列收敛于解的误差估计,所得结果是某些已知结果的改进和推广。     

Gradient dynamics in population games: Some basic results

When each player in a population game continuously adjusts her action to move up the payoff gradient, then the state variable (the action distribution) obeys a nonlinear partial differential equation. We find conditions that render gradient adjustment myopically optimal and analyze two broad classes of population games. For one class, we use known results to establish the existence and uniqueness of solutions to the PDE. In some cases, these solutions exhibit shock waves or rarefaction waves. For a second class, we use a local form of Nash equilibrium to characterize the steady state solutions of the PDE and find sufficient conditions for asymptotic convergence.     

Structural Break,Indivisibilities and Input–Output Analysis

This paper sets up and analyses a model of structural break in the framework of input–output (IO) analysis. The idea of structural break is formalized in terms of an IO model where each commodity can be produced by two alternative technologies; one of which is subjected to technologically specified indivisibility in its level of operation. The analysis of the model consists of suggesting an iterative procedure for computing its solution and developing a necessary and sufficient condition for the existence of solutions. Some results have also been derived on the question of uniqueness of a solution.     

Multivariate stable ARMA processes with time dependent coefficients

This paper considers the class of m-variate autoregressive moving average (ARMA) processes with stable innovations and time dependent coefficients. A set of suitable AR and MA regularity conditions is given to ensure existence and uniqueness of valid solutions. A simple form of the above solution is expressed in terms of one sided Green's matrix functions associated with the AR operator. We solve the prediction problem arising in this class of models. A few examples are added to support the general theory.     

Existence of proportional distribution schemes: A note

It is shown that existence of a proportional distribution scheme as discussed by Sobel (1981) is an easy consequence of uniqueness.     

Stochastic optimal growth with a non-compact state space

This paper studies the stability of a stochastic optimal growth economy introduced by Brock and Mirman [Brock, W.A., Mirman, L., 1972. Optimal economic growth and uncertainty: the discounted case. Journal of Economic Theory 4, 479–513] by utilizing stochastic monotonicity in a dynamic system. The construction of two boundary distributions leads to a new method of studying systems with non-compact state space. The paper shows the existence of a unique invariant distribution. It also shows the equivalence between the stability and the uniqueness of the invariant distribution in this dynamic system.     

On the existence,uniqueness and stability of spatial equilibrium in an open city with externalities

This paper deals with the existence, uniqueness and stability of a spatial equilibrium in an open city with external diseconomies like air pollution generated by manufacturing activities. First, assuming that both production functions and utility functions are Cobb-Douglas, we prove the existence of a spatial equilibrium under some reasonable assumptions. It is shown, however, that the uniqueness and stability of the equilibrium may not be obtained, unless the degree of externality is sufficiently small. In fact, none of the equilibria will be stable for a certain set of speeds of adjustment in the labor market and the land market, if the degree of externality is relatively large. Finally, some implications of our results are derived in regard to the application of the hedonic price concept within the context of a spatial equilibrium model.