单频网多播系统中的开环半动态功率分配算法

在单频网多播传输中,传统的全反馈动态功率分配数算法需要根据每个时隙反馈的用户瞬时信道信息进行实时的调整,所以造成了资源分配频率快、上行反馈开销大的缺点。为了克服这个缺点,提出了一个低复杂度、没有用户反馈的单频网多播开环半动态功率分配算法。首先在各小区等功率分配的假设下,根据单频网的形状信息算出各小区等价信道增益,然后再根据这个增益值,实现满足速率需求情况下的各小区功率分配。仿真结果显示,与全反馈的动态功率分配算法相比,该算法以一小部分性能损失为代价,大大减少了单频网的上行反馈和资源分配的开销,因此更适用于实际的单频网多播系统。     

林地价格及其形成

纯天然的林地和已投入人类劳动的林地都具有价格。林地价格是由林地总价值所决定的，林地总价值包括林地等效价值和林地劳动价值。林地等效价值决定林地物质价格，林地劳动价值决定林地资本价格。林地收益、供求关系、效用和稀缺程度是林地价格的重要影响因素。     

The Minimal Entropy Martingale Measure and the Valuation Problem in Incomplete Markets

Let χ be a family of stochastic processes on a given filtered probability space (Ω, F, (F_t)_t∈T, P) with T?R₊. Under the assumption that the set M_e of equivalent martingale measures for χ is not empty, we give sufficient conditions for the existence of a unique equivalent martingale measure that minimizes the relative entropy, with respect to P, in the class of martingale measures. We then provide the characterization of the density of the minimal entropy martingale measure, which suggests the equivalence between the maximization of expected exponential utility and the minimization of the relative entropy.     

An extension of the multi-output state-contingent production model

This paper presents new developments on the state-contingent theory of production under uncertainty with stochastic prices. Our main purpose is to generalize the usual finite discrete state-contingent production model to infinite dimensional, possibly uncountable spaces which look like a more realistic framework. Usual duality results are established in this general context, shedding some light on the links between risk-neutral probabilities and shadow prices. A direct generalized production risk premium is defined and is shown to be independent of the inputs level when the technology is output translation homothetic. In such a case, the technology exhibits constant absolute riskiness. We thank Bob Chambers for his helpful comments.     

基于降息环境下分期还贷利率调整的弹性分析

从央行五次降息,到商业房贷利率下限可打七折,每个购房者都在计算这笔或多或少的息差。这次调整能给购房者以多大的实惠,对于还款的具体偿还过程的本息金额又是怎样的影响,文章基于Excel的分析,对利率调整的弹性进行剖析。     

MODELING LIQUIDITY EFFECTS IN DISCRETE TIME

We study optimal portfolio choices for an agent with the aim of maximizing utility from terminal wealth within a market with liquidity costs. Under some mild conditions, we show the existence of optimal portfolios and that the marginal utility of the optimal terminal wealth serves as a change of measure to turn the marginal price process of the optimal strategy into a martingale. Finally, we illustrate our results numerically in a Cox–Ross–Rubinstein binomial model with liquidity costs and find the reservation ask prices for simple European put options.     

基于恒定市场份额模型的中国林产品出口分析

针对1992~2004年中国林产品出口规模的变动特征,采用恒定市场份额模型,对影响中国林产品出口规模变动的因素进行了分析。结果表明:中国林产品的出口明显受其产品竞争力的影响,提高林产品的竞争力对促进林产品出口具有非常积极的作用,世界林产品贸易规模的扩大和商品出口构成的优化对中国林产品的出口产生了正面影响,而市场分布效应则是负的。同时,提出通过提高林产品的竞争力、增加中国人造板的出口以及积极开拓新市场来促进中国林产品的出口等建议。     

Measuring the Volatility of Wheat Futures Prices on the LIFFE

Agricultural prices rose dramatically in 2007 and have subsequently fluctuated at high levels. This paper estimates the volatility of daily wheat futures prices on the Euronext/London International Financial Futures and Options Exchange for 1996–2012 using an exponential generalised autoregressive conditional heteroscedasticity model with a constant (price) elasticity of variance (CEV) and a broken trend. Results show that volatility is highly persistent; there is a structural break in volatility in June 2007 when volatility rose by 10%; subsequently, the wheat futures price has become more volatile; and the CEV is 0.04.     

CZ法单晶等径生长模糊控制系统设计

针对单晶等径生长过程中主要是对系统的温度和晶体测径环节的控制,介绍了一种基于模糊控制与PID算法的CZ法单晶等径生长控制系统。详细阐述系统的组成,重点介绍系统采用双闭环串级控制。最后通过仿真测试,结果表明,该系统具有对现场温度、单晶直径等参数的合理控制和调节功能,能够有效地改善系统控制性能。