大气颗粒物源解析监测中的质量控制

为确保石家庄市大气颗粒物源解析研究数据的准确性和精密性,首先结合城市自然环境、能源结构、大气环境质量现状等进行合理布点采样,同时在大气颗粒物样品采集、滤膜称量、化学组分分析等监测过程中实施了空白分析、实验室平行样分析、标准曲线绘制与核查、加标回收、有证标准物质核查等一系列质量保证措施,通过对这些质量保证措施实施情况的阐述与质量控制数据的统计、计算与分析,证明了该大气颗粒物源解析监测工作从样品采集及其称量到化学组分分析等全过程是真实有效的,表明了石家庄市大气颗粒物源解析监测数据的准确性和监测工作的可靠性。     

长历时暴雨强度公式的推求方法

近年来,随着极端暴雨事件的出现,导致城市内涝灾害频繁发生,原有降雨历时仅为2h的市政排水设计暴雨强度公式已无法满足城市暴雨设计的需求,因此就要延长暴雨采样历时,推求出长历时(24h)暴雨强度公式。针对以上问题,根据北京市提供的52a(1961-2012)原始降雨资料并进行数字化处理,结合水利的长历时特点,采用兼顾市政排水,水利排涝,内涝防治的采样方法,应用P-Ⅲ分布曲线进行频率分析后采用6种经典方法推求暴雨强度公式的参数值,优选出误差最小且满足规范要求的暴雨强度公式参数值,进而推求长历时暴雨强度公式,在此基础上与短历时暴雨强度公式比较,分析两者的差异,为城市雨水排除规划设计提供科学依据和参考。     

用人单位遵守社会保险登记时限现状研究——以北京市大兴区的社保登记时限执行情况为例

社会保险登记时限是参保单位和职工参加社会保险的重要时间界限,《中华人民共和国社会保险法》对违反登记时限的法律责任规定并不明确。目前对于新参保单位在执行登记时限规定的情况没有明确过多的关注和分析,对在执行过程中存在的问题研究也相对不多。北京市大兴区2010年7月至2012年6月参保单位的登记时限统计分析表明,建立工商—社保信息互通系统、提供科学的罚金公式等对策建议对用人单位遵守社会保险登记时限有积极的意义。     

分支水平井产能公式的可信度研究

本文仔细研究了分支水平井产能公式的架构过程,发现存在两处理论缺陷和三次数学近似。建议深入探究产能公式的架构过程,寻找合理有效的方法以革除或弥补理论缺陷。     

Insurance premiums under demand constraints

Abstract

An alternative approach to the variance principle of premium determination is explored. The approach rationalises the principle in terms of an economic theory and formalises the notion that loadings in addition to the ‘fair’ premium are related to competition and expenses.     

利用制药厂废水生产农用测土配方肥

利用制药厂的废水生产农用测土配方肥,方法可行,生产操作简单,做到废物循环利用,实现了经济、社会和环境三效益的统一.     

Do Formula or Competitive Grant Funds Have Greater Impacts on State Agricultural Productivity?

This article examines the impact of public agricultural research and extension on agricultural total factor productivity at the state level. The objective is to establish whether federal formula or competitive grant funding of agricultural research has a greater impact on state agricultural productivity. A pooled cross-section time-series model of agricultural productivity is fitted to annual data for forty-eight contiguous states over 1970–1999. Our results show that public agricultural research and agricultural extension have statistically significant positive impacts on state agricultural productivity. In addition, Hatch formula funding has a larger impact on agricultural productivity than federal competitive grant funding, and a reallocation of Hatch formula funds to competitive grant funding would lower agricultural productivity. This seems unlikely to be a socially optimal policy. Furthermore, from a cost–benefit perspective, our study shows that the social marginal annualized real rate of return to public resources invested in agricultural research is 49–62%, and to public agricultural extension, the rate is even larger.     

一类新的反Smarandache几何级数周期行列式

本文定义了一类新的反Smarandache几何级数周期行列式,并利用初等数论的方法和行列式的性质,对这类行列式进行了研究,给出了它们的通项公式。     

关于曲线积分和曲面积分教学中几个难点的突破

加强曲线、曲面积分概念讲解,标准化曲线、曲面积分的计算程序,沟通有关积分之间关系,以消除学生 对斯托克斯等公式的深奥感,有效地突破了曲线、曲面积分教学中的几个难点。     

Computing the covariance of two Brownian area integrals

We compute the expected product of two correlated Brownian area integrals, a problem that arises in the analysis of a popular sorting algorithm. Along the way we find three different formulas for the expectation of the product of the absolute values of two standard normal random variables with correlation θ . These two formulas are found: (a) via conditioning and the non-central chi-square distribution; (b) via Mehler's formula; (c) by representing the correlated normal random variables in terms of independent normal's and integration using polar coordinates.