稀土对60si_2Mn钢韧化机理的影响

本文研究稀土对60Si_2Mn钢韧化机理的影响并确定了稀土加入工艺。发现稀土对提高60Si_2Mn汽车钢板弹簧钢的断裂韧性有显著效果;对于提高冲击韧性特别是低温下的冲击韧性亦有明显效果;研究结果还表明:稀土加入60Si_2Mn钢中不仅能脱硫还可以有效地控制和改变硫化物夹杂的类型、形态与分布。文中“稀土”,在钢锭中加的为混合稀土金属,炉中及包内加入的是稀土1#合金。     

Measuring social trust and trusting the measure

Decades of rigorous quantitative scholarship have generated a wealth of knowledge regarding the causes and consequences of crossnational variations in social trust. However, while some social science disciplines have made significant contributions to this conversation, others have largely failed to do so. The field of international relations, for example, has lagged behind in producing aggregate-level scholarship on social trust. This is surprising given that (1) trust influences public opinion and thereby the incentive structure for political leaders and (2) many peacebuilding efforts directly target the levels of trust in post-conflict settings. Country-level trust scholarship in international relations and the social sciences more generally is hampered by data scarcity. The main purpose of this article is to present a new publicly available data set on aggregate levels of social trust. Relying on a set of 19 widely accepted correlates, we construct a new cross-sectional measure of the concept that covers all countries from 1946 to 2010. We then perform a series of empirical tests establishing the validity of our measure. Finally, we offer a number of bivariate analyses to demonstrate the broad utility of our new variable for scholars in the social sciences.     

On the non-Markovian structure of discrete order statistics

In this note we show that the Markov Property holds for order statistics while sampling from a discrete parent population if and only if the population has at most two distinct units. This disproves the claim of Gupta and Gupta (1981) that for geometric parent, the order statistics form a Markov chain.     

Numerical computation of bridge probabilities

This paper contains an analysis of the problem of computing the joint probability density of the honor card point count in each of four hands in the game of bridge. Efficient representation of the data is considered. Computational algorithms are given for dealing with a compressed form of the density. From the joint density, the densities of the point count in the best and worst hands are obtained. Also obtained is the conditional distribution that a partnership has m points given that one of the partners has n1 points.     

“共同富裕”是社会主义的本质属性和中国共产党人的不懈追求

共同富裕理论如同一条红线,把马列主义、毛泽东思想、邓小平理论、"三个代表"重要思想和科学发展观等重大理论贯穿起来,一脉相承,最终得出"共同富裕是社会主义的本质属性"这一高度一致的结论,对中国的社会主义实践具有重大的指导意义。     

金融资产的VaR和CVaR风险的优良估计

本文利用统计理论的优良点估计方法来估计金融市场风险的VaR和CVaR,既可避开现有方法中大量的模拟计算和参数估计等工作,又可提高估算精度.在资产-正态模型下,根据不同的风险估计要求,对金融资产的这两种风险分别提供了三种优良估计,即一致最小方差无偏估计,最佳线性次序统计量无偏估计,最佳线性次序统计量同变估计,并提供了实证分析.     

考虑复杂关联情境的城市典型生命线运行风险因素识别方法研究

城市典型生命线以供热、电力、燃气系统为代表,具有公共性强、风险性高、关联性显著的特点。研究城市典型生命线运行风险因素识别问题对于相关部门防范风险具有重要意义,但现实中由多系统、多风险因素以及各类关联形成的复杂关联情境增加了解决该问题的难度。为此,本文首先构建了具有层级网络结构的风险因素识别框架,然后提出了一种考虑复杂关联情境的风险因素识别方法,将各专家针对系统关联和风险因素关联给出的语言评价信息转化为二元语义,并将决策试验与评价实验室（DEMATEL）法和Two-Additive Choquet（TAC）积分算子扩展到二元语义环境,进而实现各类关联的综合集成,从而确定风险因素的排序和归类,便于决策者研判风险根源、明晰风险因素本质。最后,以北京某样区为例验证了所提方法的潜在应用价值,并根据识别结果制定了针对性的风险防范策略,能够为相关部门联调联动开展风险防范提供决策支持。     

机遇与挑战——写在统计学成为一级学科之际

 简要回顾了中国统计学科发展的百年历史,重点讨论了统计学科与统计教育的现状,特别是统计学完全成为一级学科后面对的大好发展机遇,以及在做大的基础上如何做强统计学科需要我们重视、研究和解决的主要问题。     

Optimal Security Investments and Extreme Risk

In the aftermath of 9/11, concern over security increased dramatically in both the public and the private sector. Yet, no clear algorithm exists to inform firms on the amount and the timing of security investments to mitigate the impact of catastrophic risks. The goal of this article is to devise an optimum investment strategy for firms to mitigate exposure to catastrophic risks, focusing on how much to invest and when to invest. The latter question addresses the issue of whether postponing a risk mitigating decision is an optimal strategy or not. Accordingly, we develop and estimate both a one‐period model and a multiperiod model within the framework of extreme value theory (EVT). We calibrate these models using probability measures for catastrophic terrorism risks associated with attacks on the food sector. We then compare our findings with the purchase of catastrophic risk insurance.     

On the wald,lagrangian multiplier and likelihood ratio tests when the information matrix is singular

Summary Modified formulas for the Wald and Lagrangian multiplier statistics are introduced and considered together with the likelihood ratio statistics for testing a typical null hypothesisH ₀ stated in terms of equality constraints. It is demonstrated, subject to known standard regularity conditions, that each of these statistics and the known Wald statistic has the asymptotic chi-square distribution with degrees of freedom equal to the number of equality constraints specified byH ₀ whether the information matrix is singular or nonsingular. The results of this paper include a generalization of the results of Sively (1959) concerning the equivalence of the Wald, Lagrange multiplier and likelihood ratio tests to the case of singular information matrices.