一种基于CMA和DDLMS算法的双模式盲均衡算法

为进一步改进盲均衡算法收敛速度慢、稳态误差大、计算复杂度高等问题,提出一种切换模式和加权模式联合CMA(Constant Modulus Algorithm)+DDLMS(Direct Decision Least Mean Square)双模式盲均衡算法。综合切换双模式盲均衡算法和加权双模式盲均衡算法的优缺点,对切换、加权模式联合的CMA+DDLMS双模式盲均衡算法进行仿真。在不同信噪比条件下,对CMA算法、MCMA(Modified CMA)算法、DDLMS算法和CMA+DDLMS双模式盲均衡算法进行仿真,结果表明,所提算法收敛速度快,约为600个符号;稳态误差小,约为0.1;误码率小,在信噪比为25 dB时,误码率约为10-6。该算法可广泛应用于无线通信、光通信、声呐和雷达等众多领域。     

Regime switching models for the Mexican peso

The Mexican peso has shown long periods of tranquility that suddenly give rise to short volatile periods. We characterize this exchange rate process by estimating a series of regime switching regressions and comparing the different specifications as pioneered by Meese and Rogoff [J. Int. Econ. 14 (1983) 3]. We find evidence for two clearly identified regimes: one with an appreciating trend and low volatility, and another with large depreciations and high volatility. We use the estimated model to explain the bias implied in the peso forward market. Finally, we show that duration dependence or fundamentally driven transition probabilities do not improve the model's forecasting power.     

Regulatory Actions under Adjustment Costs and the Resolution of Scientific Uncertainty

Food system regulators often decide whether to ban existing practices or approve new technologies without conclusive scientific evidence on possible damage and knowing that resolution is likely in the future. In a model with three decision points and stochastic resolution of uncertainty, we study interactions between expected losses due to regulation and information availability when a regulator is deciding on an early reversible ban and on a later reversible ban. Adjustment costs create inertia concerning intermediate signals such that earlier decisions are not overturned, and also a bias against imposing an early ban. The prospect of more later-stage information can increase or decrease the incentive to ban early, but research decreases the incentive to ban early.     

Demographic shift, relative costs and the allocation of local public consumption in Norway

Local government responses to shifting demand and supply conditions are investigated. The desired allocation of local public consumption is determined in a voter group decision model where different age groups compete for services within an exogenous budget constraint. The model is implemented in an AIDS demand system built into a partial adjustment framework. The estimates indicate that the dramatic shift in the age composition of the population from the young to the elderly during the period studied has led to higher educational spending per pupil and less health care services per elderly. Age groups in decline are able to resist reallocations and gain in terms of spending per head.     

The Effect of Market Regimes on Style Allocation

We analyse time-varying risk premia and the implications for portfolio choice. Using Markov Chain Monte Carlo (MCMC) methods, we estimate a multivariate regime-switching model for the Carhart (1997) four-factor model. We find two clearly separable regimes with different mean returns, volatilities, and correlations. In the High-Variance Regime, only value stocks deliver a good performance, whereas in the Low-Variance Regime, the market portfolio and momentum stocks promise high returns. Regime-switching induces investors to change their portfolio style over time depending on the investment horizon, the risk aversion, and the prevailing regime. Value investing seems to be a rational strategy in the High-Variance Regime, momentum investing in the Low-Variance Regime. An empirical out-of-sample backtest indicates that this switching strategy can be profitable, but the overall forecasting ability for the regime-switching model seems to be weak compared to the iid model.     

我国医疗保健行业股指收益率波动特征与杠杆效应

本文运用SWARCH模型分析了我国医疗保健板块收益率的波动,并将医疗保健板块收益率与上证综指、深证成指收益率的SWARCH模型的估计结果进行比较,得出以下结论:医疗保健指数收益率序列呈现出低、中、高三种波动状态,样本区间主要分布于中波动状态,低波动状态的平均持续期最长、中波动状态的平均持续期居中、高波动状态的平均持续期最短,医疗保健指数收益率波动杠杆效应显著;我国股市医疗保健板块收益率波动状态之间的差异高于沪深综指波动状态的差异,医疗保健指数收益率与沪深综指收益率区制转移趋同,但存在着细微差异;医疗保健指数收益率各区制间转移相对频繁,每种波动状态的平均持续期较短,股市医疗保健板块收益率对新信息的反应更为敏感。     

卫星通信站极化隔离度下降的排查及解决方法

针对卫星通信站接收交叉极化隔离度下降的问题,首先利用Matlab软件绘制了隔离度与 极化角、线圆转换器偏差的关系曲线,然后通过实测值和公式相比较,推导出偏差理论值。 最后,根据推导出的结论,通过工程实践解决了极化隔离度下降的问题,调整后测试的结果 也验证了该方法的可行性。     

海上遇险搜救综合通信系统的设计与实现

为了提高我国海上搜救应急反应的调度、指挥能力,利用现代通信、计算机、计算机 电信合成（CTI）等技术,实现了海上遇险搜救综合通信系统。该系统采用程控调度交换和 无线电台适配的方案,使用无线电台适配器将无线通信转换为有线通信,再通过程控交换机 将各级海上搜救中各类卫星、语音电话、视频系统等异构终端综合互联,实现有线通信系统 与无线通信系统的无缝连接,从而为值班和搜救指挥人员提供专业、便捷的通信、操作手段 ,提高指挥判断的准确性和效率。     

Customer capabilities,switching costs,and bank performance

Customers develop switching costs when they invest time and effort to develop capabilities required to optimally use a given product. Such capabilities are likely to be firm specific and cannot be transferred perfectly to competitors' product offerings. Customers who face switching costs are likely to remain with the same firm and consume complementary products that meet their needs. Thus, firms can achieve competitive advantage by exploiting customers' switching costs. In this paper, we hypothesize that the extent to which firms can benefit from customers' switching costs is contingent upon the firms' internal cross‐selling capabilities. We use online banking data to test our hypotheses and find that customers' switching costs contribute to banks' profitability only in the presence of high levels of internal cross‐selling capabilities. Copyright © 2012 John Wiley & Sons, Ltd.