弱扩展原理

本文引入了弱扩展原理,并研究了它的一些性质,最后给出了弱扩展原理的三种等价表现形式。     

From Discrete- to Continuous-Time Finance: Weak Convergence of the Financial Gain Process1

Conditions suitable for applications in finance are given for the weak convergence (or convergence in probability) of stochastic integrals. For example, consider a sequence Sⁿ of security price processes converging in distribution to S and a sequence θⁿ of trading strategies converging in distribution to θ. We survey conditions under which the financial gain process θⁿ dSⁿ converges in distribution to θ dS. Examples include convergence from discrete- to continuous-time settings and, in particular, generalizations of the convergence of binomial option replication models to the Black-Scholes model. Counterexamples are also provided.     

微弱LFM信号的FrFT检测能力分析

基于分数阶傅里叶变换（FrFT）检测线性调频（LFM）信号广泛应用于雷达、通信、声呐和电子战领域，但缺乏对检测灵敏度的定量分析。为此，研究了FrFT对微弱LFM信号的检测能力。根据FrFT思想和二元假设检验理论，推导了检测概率和虚警概率的数学表达式。由于表达式是关于LFM信号频谱的函数，因此区分快变信号和慢变信号对LFM的频谱进行了合理近似。基于接收机工作特性曲线分析了FrFT检测LFM信号的灵敏度。仿真比较了FrFT与传统傅里叶变换（FT）对微弱LFM信号的检测能力，结果表明FrFT对LFM信号的检测灵敏度和信号累积能力均优于FT。     

Dynamic Arbitrage‐Free Asset Pricing with Proportional Transaction Costs

This paper studies multiperiod asset pricing theory in arbitrage‐free financial markets with proportional transaction costs. The mathematical formulation is based on a Euclidean space for weakly arbitrage‐free security markets and strongly arbitrage‐free security markets. We establish the weakly arbitrage‐free pricing theorem and the strongly arbitrage‐free pricing theorem.     

Optimal portfolios when stock prices follow an exponential Lévy process

We investigate some portfolio problems that consist of maximizing expected terminal wealth under the constraint of an upper bound for the risk, where we measure risk by the variance, but also by the Capital-at-Risk (CaR). The solution of the mean-variance problem has the same structure for any price process which follows an exponential Lévy process. The CaR involves a quantile of the corresponding wealth process of the portfolio. We derive a weak limit law for its approximation by a simpler Lévy process, often the sum of a drift term, a Brownian motion and a compound Poisson process. Certain relations between a Lévy process and its stochastic exponential are investigated.Received: January 2003Mathematics Subject Classification: Primary: 60F05, 60G51, 60H30, 91B28; secondary: 60E07, 91B70JEL Classification: C22, G11, D81We would like to thank Jan Kallsen and Ralf Korn for discussions and valuable remarks on a previous version of our paper. The second author would like to thank the participants of the Conference on Lévy Processes at Aarhus University in January 2002 for stimulating remarks. In particular, a discussion with Jan Rosinski on gamma processes has provided more insight into the approximation of the variance gamma model.     

实施负所得税制的必要性和可行性

负所得税制度首先由美国芝加哥大学的米尔顿·弗里德曼提出,后来又在西方经济学界得到了发展。本文则针对我国目前存在的弱势群体、城乡收入差距和内需不足等实际问题,分析了负所得税制度在我国实施的必要性和可行性,同时还运用负所得税制度的基本思想提出了超额累退所得税制     

错层板柱与普通板柱结构体系的弹塑性分析

错层板柱结构用地率高、层高低、造价节约,在停车库建筑中应用广泛[1]。但错层使楼板错置,削弱了楼板协调结构整体受力的性能。同时形成竖向短构件,受力集中。本文通过时程分析法对对两种结构进行水平地震作用下弹塑性分析,找出错层板柱结构的的抗震薄弱点。     

强弱电干扰与电网接地方式

伴随着世界科技的飞速发展,遍布世界各地的有线通讯和无线通讯技术,已经构成了一个密集的网络系统。同时,为了与国民经济的发展相协调,电力网进行了扩建,建设了很多变电站,无论是在地下还是地上,都构成了一个复杂的电网系统。强电和弱电这两大网络与国民的生活紧密相连。这势必将导致电网和道路之间的干扰,本文就此干扰的矛盾进行了相关的分析,以期为解决它们之间的问题提供帮助。     

La Ley de Okun y la flexibilidad laboral en México: un análisis de cointegración, 1997Q3-2014Q1

Because the labor flexibility has become an increasing condition in labor markets, we estimated the effect of labor flexibility on the unemployment rate in Mexico for 1997Q3-2014Q1. For this fact, we estimated a VECM(4) inspired on the Okun's Law which includes a labor flexibility index, measured by the ratio of the temporary contracts to the total employees in the formal labor market. As expected by the Okun's Law (1962), we found a negative relationship between GDP and the unemployment rate. However, the most interesting result is that the labor flexibility index exhibits an increasing effect on the unemployment rate with an elasticity of 1.28.