长周期光纤光栅研究现状分析

光纤光栅在光纤通信和光纤传感等领域有着广泛的应用,其中长周期光纤光栅是近年来光纤光栅研究领域的热点之一．该文在总结长周期光纤光栅研究现状的基础上,着重介绍了高频CO2激光脉冲写入长周期光纤光栅的新方法。     

论远程教育中多媒体教学资源的应用效果

分析和评价了我国现代远程教育多媒体教学资源的现状和应用效果,针对多媒体教学资源中存在的问题,提出以学生为中心的理念,对多媒体教学资源进行开发设计;用开放性原则来进一步完善多媒体教学资源的建设;从最优化组合的要求对现有的多媒体教学资源进行整合。     

发展远程教育是实现西部地区教育腾飞的必然选择

随着计算机技术、网络技术和电子通信技术的迅速发展和应用,带来教育信息资源的极大丰富和教育手段的多样化.要实现西部地区的经济腾飞,必须使其教育腾飞,要使教育腾飞,必须解放思想,勇于创新,改变传统教育模式,大力发展远程教育是必然选择.     

新论土家语的判断句

土家语的判断句,归纳起来只有肯定判断和否定判断两大类,其中又有隐性判断和显性判断的区别,判断形式多种多样,判断词也极为丰富。说土家语“无判断词”和“判断动词是从汉语里吸收的”是以偏概全,应予纠正。     

什么样的民族政策可以保证国家长治久安(上)

“第二代民族政策”没有新意;“第二代民族政策”观点举证严重失实;本文从理论到实际例证,对“第二代民族政策”提出了质疑.     

Estimating multivariate autoregressive moving average models by fitting long autoregressions

Some simple methods for the estimation of mixed multivariate autoregressive moving average time series models are introduced. The methods require the fitting of a long autoregression to the data and the computation of consistent initial estimates for the parameters of the model. After these preliminaries the estimators of the paper are obtained by applying weighted least squares to a multivariate auxiliary regression model. Two types of weight matrices are considered. Both of them yield estimators which are strongly consistent and asymptotically normally distributed. The first estimators are also asymptotically efficient while the second ones are not fully efficient but computationally simple. A simulation study is performed to illustrate the behaviour of the estimators in finite samples.     

Time varying long memory parameter estimation for locally stationary long memory processes

The semiparametric estimators of time varying long memory parameter are investigated for locally stationary long memory processes. The GPH estimator and the local Whittle estimator are considered. Under some mild regularity assumptions, the weak consistency and the asymptotic normality of the estimators are obtained. The finite sample performance of the estimators is discussed through a small simulation study.     

Nonparametric beta kernel estimator for long and short memory time series

In this article we introduce a nonparametric estimator of the spectral density by smoothing the periodogram using beta kernel density. The estimator is proved to be bounded for short memory data and diverges at the origin for long memory data. The convergence in probability of the relative error and Monte Carlo simulations show that the proposed estimator automatically adapts to the long- and the short-range dependency of the process. A cross-validation procedure is studied in order to select the nuisance parameter of the estimator. Illustrations on historical as well as most recent returns and absolute returns of the S&P500 index show the performance of the beta kernel estimator. The Canadian Journal of Statistics 48: 582–595; 2020 © 2020 Statistical Society of Canada     

长输管道故障树及可靠性增长对策

天然气大部分通过远距离运输和销售,管道运行的可靠性对天然气市场具有重要的影响。分析讨论了影响道运行可靠性的主要因素,并据此提出提高管道运行可靠性的对策与措施,供管道运行管理者参考。     

语句感知难度的层次分析佐证

汉语中存在许多名词修饰名词的偏正结构,如“父亲的父亲的父亲”等,这种结构潜在多种切分可能。通过语句感知难度的计算方法,可以发现这种结构的层次具有“左向切分”的普遍性。同时,语句感知难度的计算对一些传统的语句切分提出了质疑。