无拍频控制技术在新一代CRH380CL型高速动车组上的应用

高速动车组技术的迅猛发展对牵引变流器的性能提出了更高的要求。在动车组传动系统中,单相脉冲整流器工作时,会在中间直流环节产生2倍于电网频率的脉动分量,该脉动分量传递到逆变器输出侧会在电机上产生拍频现象,引起转矩脉动和电机过热。     

A Bayesian analysis of a variance decomposition for stock returns

We apply Bayesian methods to study a common vector autoregression (VAR)-based approach for decomposing the variance of excess stock returns into components reflecting news about future excess stock returns, future real interest rates, and future dividends. We develop a new prior elicitation strategy, which involves expressing beliefs about the components of the variance decomposition. Previous Bayesian work elicited priors from the difficult-to-interpret parameters of the VAR. With a commonly used data set, we find that the posterior standard deviations for the variance decomposition based on these previously used priors, including “non-informative” limiting cases, are much larger than classical standard errors based on asymptotic approximations. Therefore, the non-informative researcher remains relatively uninformed about the variance decomposition after observing the data. We show the large posterior standard deviations arise because the “non-informative” prior is implicitly very informative in a highly undesirable way. However, reasonably informative priors using our elicitation method allow for much more precise inference about components of the variance decomposition.     

A characterization of exact non-atomic market games

Continuous exact non-atomic games are naturally associated to certain operators between Banach spaces. It thus makes sense to study games by means of the corresponding operators. We characterize non-atomic exact market games in terms of the properties of the associated operators. We also prove a separation theorem for weak compact sets of countably additive non-atomic measures, which is of independent interest.     

基于VAR模型实证分析云南省教育投入与经济增长的关系

采用向量自回归模型（VAR）,通过协整检验、格兰杰因果检验、脉冲响应函数对云南省教育投入与经济增长的关系进行实证分析,结果表明云南省教育投入与经济增长之间存在着互为因果的长期均衡关系,教育投入对经济增长的贡献率为24．3％。     

外汇储备对我国物价水平的影响——基于协整检验与误差修正模型的分析

协整和格兰杰因果检验结果表明,我国外汇储备与物价水平存在协整关系,且外汇储备是物价水平的格兰杰原因,表明外汇储备增加将对通货膨胀形成压力。但从误差修正模型的检验结果看,我国外汇储备对物价水平的影响在短期内较为有限,其主要原因是我国央行短期内进行大量的外汇冲销操作。因此,我国需要采取有效的措施来缓解通胀压力,如加大央行公开市场业务操作、改革外汇管理体制、适当放宽汇率浮动幅度以及合理使用我国现有外汇储备等。     

基于小波变换和支持向量的国际原油价格预测

本文将小波分析与支持向量回归结合应用于国际原油价格预测,通过小波多尺度分析方法将油价时间序列分解为长期趋势和随机扰动项,然后采用支持向量回归对分解后的油价长期趋势进行预测。油价长期趋势的预测采用多因素预测方法,主要考虑市场供需基本面、库存、经济、投机等因素对石油价格走势的影响,建立多输入单输出的支持向量回归模型。实证研究表明,支持向量回归模型具有较高的预测性能,对原油价格长期趋势预测中,该方法比回归方法的预测精度高。     

基于VAR模型的山东省经济增长波动分析

本文通过建立向量自回归模型,运用脉冲响应函数和预测方差分解的方法对山东省经济增长的波动情况进行了实证分析。研究结果表明:各变量对山东经济增长的影响均不太明显。这说明山东经济一直保持稳定快速发展的势头。     

The effects of oil price shocks on expenditure category CPI

In this study, we apply a two-block structural vector autoregressive (VAR) model proposed by Kilian and Park (2009) in order to investigate the dynamic effects of changes in oil price on the expenditure category consumer price index (CPI) in the United States and Japan. Our results confirm that each expenditure category price index responded very differently to the same structural shock, and that whether changes in oil price function as a positive stimulus or a negative shock for the individual expenditure category prices also depends on the kind of underlying shock that drives the changes in oil price. Finally, our results also reveal that the manner in which changes in oil price affect each expenditure category price differs between the United States and Japan and these detailed-level differences may lead to aggregate-level differences in the price response of both countries to changes in oil price.     

Common dynamics of nonenergy commodity prices and their relation to uncertainty

The purpose of this article is to improve the empirical evidence on commodity prices in various dimensions. First, we attempt to identify the extent of comovements in 44 monthly nonenergy commodity price series in order to ascertain whether the increase in comovement is a recent term phenomenon. Second, we attempt to determine the role of uncertainty in determining comovements among nonenergy prices in the short run. We diagnose the overall comovement using a dynamic factor model estimated by principal components. A factor-augmented vector autoregressive approach is used to assess the relationship of fundamentals, financial and uncertainty variables with the comovement in commodity prices. We find a greater synchronization among raw materials since December 2003. Since that date, uncertainty has played an important role in determining short-run fluctuations in nonenergy raw material prices.     

讨论矩阵的特征值与行列式的关系

利用矩阵的特征值解决行列式的问题。