Some properties of modified integrated squared error estimators for the stable laws

The estimation procedure of Paulson, Holcomb and Leitch (1975) for the parameters of the stable laws is shown to be similar in spirit to the modified X²minimum procedure. This observation suggests that a class of modified integrated squared error procedures may be developed for the stable laws as well as much more generally. For the stable case, some influence curves, asymptotic covariances, and efficiencies are given, and the robustness of maximum likelihood estimators is discussed.     

具有时滞的Hopfield神经网络的周期解

假设具有时滞的Hopfield神经网络的每个输出响应函数是满足Lipschitz条件的有界函数,当该网络的输入信号始终以正常数ω为周期,并且在网络参数满足一定的条件时,通过构造适当的Lyapunov泛函的方法,得到了该类网络必存在唯一的ω-周期解,并且其余各解都按指数收敛于该周期解的一些判据,通过实例对所得到的判据进行了直观性解释。     

稳定币Libra的风险与规制路径

Facebook的稳定币Libra项目，引起各国金融界和监管机构的关注和警惕。Libra在技术成熟度、稳定性、安全性、应用场景等方面均占有优势，也将带来种种潜在风险，增大各国外汇管制难度，弱化各国货币政策实施效果，增加反洗钱和反恐怖融资的难度。对此，中国监管机构应首先明确Libra稳定币的法律属性。其次，中国要调整监管手段及外汇管理的具体方式。最后，有区块链与数字货币技术研发实力的互联网巨头可尝试发行与人民币1：1挂钩的稳定币。监管机构制定出台相应法律政策前，可先行指导和推动上述商业巨头自己创生稳定币的治理规则。在中国互联网巨头探索稳定币发行的成熟经验和商业模式基础上，由中国央行加以借鉴，最后搭建法定的数字货币发行体系。     

Minimax Designs for the Stability of Slope Estimation on Second-order Response Surfaces

In this paper, designs for the stability of the slope estimation on a second-order response surface are considered. Minimization of the point dispersion measure, which is maximized over all points in the region of interest is taken as the optimality criterion, and the minimax properties in some class of designs are derived in spherical and cubic regions of interest. We study the efficiencies of the minimax designs relative to other optimal designs with various criteria.     

Asymptotic properties of randomly indexed sequences of random variables

Conditions are given for a randomly indexed sequence of random variables to converge weakly. The key concept employed is the so-called generalized Anscombe condition. The results give a method of determining sequential stopping rules, which have the required accuracy of estimation of an unknown parameter in the case when the observations are not necessarily independent and identically distributed.     

气力输送设备综述

对气力输送设备—仓式泵的应用与研究进行了探讨 ,针对仓式泵的缺点 ,介绍了一种能连续供料的新型气力输送设备。稳流仓式泵由三个串联的仓组成 ,具有供料连续、料流均匀、脉动现象小等优点。该泵不仅适用于高浓度气力输送 ,也适用于稀相气力输送     

Hopfield型神经网络的全局指数稳定性(英文)

研究了Ｈｏｐｆｉｅｌｄ型神经网络的全局指数稳定性,就活化函数严格单增和严格单增但增益有界的情况,提出了保证网络全局指数稳定的充分判据。对活化函数严格单增权矩阵对角稳定的情况,以简约的形式,给出网络全局指数稳定的收敛速率。     

A statistical approach to social network monitoring

Social network monitoring consists of monitoring changes in networks with the aim of detecting significant ones and attempting to identify assignable cause(s) contributing to the occurrence of a change. This paper proposes a method that helps to overcome some of the weaknesses of the existing methods. A Poisson regression model for the probability of the number of communications between network members as a function of vertex attributes is constructed. Multivariate exponentially weighted moving average (MEWMA) and multivariate cumulative sum (MCUSUM) control charts are used to monitor the network formation process. The results indicate more efficient performance for the MEWMA chart in identifying significant changes.     

Fractionally integrated GARCH model with tempered stable distribution: a simulation study

With the growing availability of high-frequency data, long memory has become a popular topic in finance research. Fractionally Integrated GARCH (FIGARCH) model is a standard approach to study the long memory of financial volatility. The original specification of FIGARCH model is developed using Normal distribution, which cannot accommodate fat-tailed properties commonly existing in financial time series. Traditionally, the Student-t distribution and General Error Distribution (GED) are used instead to solve that problem. However, a recent study points out that the Student-t lacks stability. Instead, the Stable distribution is introduced. The issue of this distribution is that its second moment does not exist. To overcome this new problem, the tempered stable distribution, which retains most attractive characteristics of the Stable distribution and has defined moments, is a natural candidate. In this paper, we describe the estimation procedure of the FIGARCH model with tempered stable distribution and conduct a series of simulation studies to demonstrate that it consistently outperforms FIGARCH models with the Normal, Student-t and GED distributions. An empirical evidence of the S&P 500 hourly return is also provided with robust results. Therefore, we argue that the tempered stable distribution could be a widely useful tool for modelling the high-frequency financial volatility in general contexts with a FIGARCH-type specification.     

诸葛亮的接班人——蒋琬

诸葛亮选定的接班人是蒋琬。他早年便深受诸葛亮赏识,被誉为"社稷之器"。执掌国政后,坚持"以安民为本"的执政理念,发展经济,调整战略,安定民生,协调君臣,维护了蜀汉的稳定,做到"边境无虞,邦家和一",堪称继武诸葛亮的一代贤相。论历史地位,他应该高于姜维;而其执政理念,更是永远垂范后世。