增长曲线模型的两步估计及其优良性

讨论了增长曲线模型回归参数阵的两步估计问题,给出了回归参数阵的可估函数的两步估计具有无偏性的一个基本结论,并验证了两种常见两步估计均具有无偏性．     

双大Reynolds数问题的混合方法

讨论双大Reynolds数问题,首先将解析解分解为光滑部分和奇性部分,对这两部分都做了上界估计;然后将解析解进行2阶渐近展开;最后提出混合算法．混合算法的主要思想是引入过渡点将区域分为粗网格区域和细网格区域,在这些网格区域采用等步长．在细网格区域采用有限元法,在粗网格区域采用迎风差分格式．混合算法结合了渐近解、数值解和BVT法的优势,是一个实用、有效的算法。     

考虑零售商策略性库存的双渠道供应链定价及协调

针对双渠道供应链环境下,零售商将前期采购的部分产品作为策略性库存用于后期销售的情形,建立了制造商为主方的两周期Stackelberg动态博弈模型,分析了零售商持有策略性库存对双渠道供应链成员定价决策的影响。研究结果表明,零售商可以通过持有策略性库存影响制造商的批发价格决策,进而影响传统零售渠道和电子直销渠道之间的零售价格竞争。特别地,当单位库存持有成本较小时,持有策略性库存能够增加零售商利润。同时,为了缓解渠道冲突和双重边际化问题,构造了基于电子渠道直销价格的批发价格折扣和固定转移支付的组合契约。最后,通过数值分析,验证了此种组合契约同时协调零售商策略性库存决策和双渠道供应链成员两周期定价决策的有效性。     

中距协同空战决策过程二次聚类重构与评估

未来空战将以中距空战为主,找出导致中距空战结果的原因是开展贴近实际的中距空战智能决策需解决的重要问题。针对空战训练过程中记录数据分布的复杂特点,建立了中距协同空战训练评估模型,提出了基于高阶导数聚类和相对模糊熵聚类的二次聚类方法,计算编队协同决策集,实现编队中距协同空战决策过程重构。以编队协同搜索和协同机动决策的角度,寻找编队协同决策与中距空战结果的相关性,并通过实例评估验证了聚类算法的合理性。     

具有两种不同服务的负顾客M/G/1排队系统

考虑单服务台提供两种不同服务的负顾客M/G/1排队模型,每个正顾客接受第一种服务后以概率θ(0≤θ≤1)进行第二种服务,或者以概率1-θ离开系统,第二种服务完成后也离开系统.服务规则是先到先服务(FCFS).在正顾客接受两种服务的过程中均可能有负顾客到达,负顾客不接受服务,只起抵消正顾客的作用,抵消正在接受服务的顾客(RCH).通过补充变量法和状态转移方程求得了系统稳态队长的概率母函数.     

Prediction in the two‐way random‐effect model with heteroskedasticity

In this paper we extend Taub (1979) approach for prediction in the context of the variance components model. The extension obtained is based on the two‐way random‐effect model with heteroskedasticity. Prediction functions are then obtained in three heteroskedasticity cases (heteroskedasticity on the individual term , heteroskedasticity on the composite term ?_it, and heteroskedasticity on the temporal term ). Copyright © 2008 John Wiley & Sons, Ltd.     

二维发汗控制方程的直线解法及其收敛性

对二维发汗控制方程建立了直线解法,可用任何解常微分方程组的数值方法求解。对固定边界（非烧蚀）和活动边界（烧蚀）情形分别进行讨论。在某些假定下给出了直线法的收敛性。     

The utilization of two‐metre Countryside Stewardship Scheme grass margins by the gatekeeper Pyronia tithonus (L)

The utilization of 2‐m Countryside Stewardship Scheme (CSS) grass margins by Pyronia tithonus was investigated during the period 1997–2000 at three farms in Essex, UK. The aims of the research were to investigate whether 2‐m grass margins established using the CSS would provide suitable habitat for P. tithonus. Overall, there was no significant difference between P. tithonus abundance on the 2‐m grass margins and the control sections without margins, but significantly more P. tithonus were observed on the 2‐m grass margins in 2000 than in 1997. There was a strong relationship between P. tithonus abundance and the presence of hedgerows, and significantly more P. tithonus were recorded on 2‐m grass margins next to hedgerows than on 2‐m grass margins established in areas without adjacent hedgerows. It was suggested that P. tithonus would benefit most from habitats with 2‐m grass margins sown with a seed mixture containing a range of fine‐leaved grasses and wildflowers, next to a hedgerow, and managed in accordance with current practices.     

从Techné特刊看现代西方技术哲学的转向

在国际技术哲学学会(SPT)成立35周年、Techné创刊15周年之际,Techné在2010年第2期组织了一期特刊,回顾了SPT的建制化发展历程,考察了技术哲学过去35年的历史演变,总结了在这一时期取得的主要成就,并对未来技术哲学的新动向做了展望。这有助于我们更好地了解现代技术哲学的发展状况,对我国技术哲学今后的发展有重要的启示意义。     

Gas-liquid phase coexistence and finite-size effects in a two-dimensional Lennard-Jones system

The gas-liquid phase coexistence in a two-dimensional Lennard-Jones system is investigated using Maxwell construction method together with molecular dynamics simulations.The results of phase coexistence in different truncations of the potential are compared with data obtained from the literature,and the corresponding critical properties calculated.The crossover from Ising-like to mean field behavior is observed and confirmed as the temperature approaches the critical point from below.Performing simulations on systems with different sizes,we find that a finite size effect is more significant than those shown in most of the previous results,and a lower critical temperature is obtained when the full extent of this finite size effect is considered.