拉普拉斯反变换的一种数值算法

本文介绍了一种便于在计算机辅助下实现的拉普拉斯反变换的近似算法，并对该算法的使用条件和适用范围进行了讨论。     

探析环境风险预防原则在我国的适用

随着人类经济活动和技术开发活动的不断扩大,人类的生存环境乃至人的生命和健康越来越面临巨大的风险.为此,《里约宣言》第15项全面推出适用环境风险预防原则.环境风险预防原则以科学不确定性为特征及前提,在适用中给予行政机关(开发者)以自由裁量权.行政机关(开发者)若有越权或者滥用职权等违法行为,则应追究其法律责任.相比我国在该原则研究中的匮乏,日本的研究较为深刻并为我们提供了比较法上的参照.     

晶闸管有源逆变探析

本文分析了有源逆变的条件,并以单相全控桥式有源逆变为例,分析了其工作过程及波形,指出了影响有源逆变成败的主要因素及防护措施,对实际工作有一定的指导意义.     

Modelling cell generation times by using the tempered stable distribution

Summary.  We show that the family of tempered stable distributions has considerable potential for modelling cell generation time data. Several real examples illustrate how these distributions can improve on currently assumed models, including the gamma and inverse Gaussian distributions which arise as special cases. Our applications concentrate on the generation times of oligodendrocyte progenitor cells and the yeast Saccharomyces cerevisiae . Numerical inversion of the Laplace transform of the probability density function provides fast and accurate approximations to the tempered stable density, for which no closed form generally exists. We also show how the asymptotic population growth rate is easily calculated under a tempered stable model.     

Regulating Under Uncertainty: Newsboy for Exposure Limits

Setting action levels or limits for health protection is complicated by uncertainty in the dose-response relation across a range of hazards and exposures. To address this issue, we consider the classic newsboy problem. The principles used to manage uncertainty for that case are applied to two stylized exposure examples, one for high dose and high dose rate radiation and the other for ammonia. Both incorporate expert judgment on uncertainty quantification in the dose-response relationship. The mathematical technique of probabilistic inversion also plays a key role. We propose a coupled approach, whereby scientists quantify the dose-response uncertainty using techniques such as structured expert judgment with performance weights and probabilistic inversion, and stakeholders quantify associated loss rates.     

A revisit of the distribution of linear combinations of Dirichlet components

Provost and Cheong (2000 Provost, S. B., and Y.-H. Cheong. 2000. On the distribution of linear combinations of the components of a Dirichlet random vector. The Canadian Journal of Statistics 28 (2):417–25.[Crossref], [Web of Science ®] , [Google Scholar]) show the importance of the distribution of linear combinations of components of a Dirichlet random vector to quadratic forms and their ratios in statistics, which can be applied in a variety of contexts. The c-characteristic function has been shown to be very useful and more practical in some distributions that are hard to manage with the traditional characteristic functions. The importance of the distribution of linear combinations of components of a Dirichlet random vector to quadratic forms and their ratios in statistics, which can be applied in a variety of contexts, is well known. We first provide its inversion formula which is practical in determining the distribution function of a random variable when its c-characteristic function is known. We then use this inversion formula to find an expression of probability density function of linear combinations of components of any Dirichlet vector. This would generalize the currently well known results.     

论环境民事侵权诉讼中的举证责任倒置

举证责任的合理分配在民事侵权诉讼中能平衡诉讼双方的权利地位,一般举证责任分配原则难以契合环境侵权的特殊性。举证责任倒置原则在环境侵权诉讼中的适用有着平衡主体双方地位、降低证据采集难度,提高证据的效力等效果。但是我国目前立法与司法实践中关于环境侵权诉讼的举证责任倒置仍有待完善。     

On directional Metropolis–Hastings algorithms

New Metropolis–Hastings algorithms using directional updates are introduced in this paper. Each iteration of a directional Metropolis–Hastings algorithm consists of three steps (i) generate a line by sampling an auxiliary variable, (ii) propose a new state along the line, and (iii) accept/reject according to the Metropolis–Hastings acceptance probability. We consider two classes of directional updates. The first uses a point in ⁿ as auxiliary variable, the second an auxiliary direction vector. The proposed algorithms generalize previous directional updating schemes since we allow the distribution of the auxiliary variable to depend on properties of the target at the current state. By letting the proposal distribution along the line depend on the density of the auxiliary variable, we identify proposal mechanisms that give unit acceptance rate. When we use direction vector as auxiliary variable, we get the advantageous effect of large moves in the Markov chain and hence the autocorrelation length of the samples is small. We apply the directional Metropolis–Hastings algorithms to a Gaussian example, a mixture of Gaussian densities, and a Bayesian model for seismic data.     

跨境欲望及其逆反——论国家形象宣传片·角度篇

《国家形象宣传片·角度篇》在主流的民族-国家叙事中有一定非主流的色彩。相较于以往对于中国形象的表现,《角度篇》由本质转向关系来定位中国,体现了中国人对于现代化跨境的想象和欲望,但随着中国国力渐长,我们对国家更加自信,也体现于宣传片中的跨境欲望的逆反。除此之外,《角度篇》对敏感问题的处理也有值得思考之处。     

Unique decomposition of low-order time series

ABSTRACT

We give necessary and sufficient conditions on the parameters of processes ARMA(1, 1) and ARMA(2, 1) for representation of each as unique sums of independent simpler ARMA processes, including deduction from the sum process of the innovation variances of these summands. This work on inversion is motivated by examples in the article of Granger and Morris (1976 Granger, C.W.J., Morris, M.J. (1976). Time series modelling and interpretation. J. Roy. Statist. Soc., Ser. A 139:246–257.[Crossref] , [Google Scholar]) and by our earlier article (Ku and Seneta, 1998 Ku, S., Seneta, E. (1998). Practical estimation from the sum of AR(1) processes. Commun. Statist. Simul. Computat. 27:981–998.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]), to which the present article is a self-contained sequel. The theory is illustrated by the analysis of tree ring data.