质量功能配置中基于ANN的顾客需求重要度评估方法

提出了一种基于人工神经网络（ＡＮＮ）的质量功能配置（ＱＦＤ）中顾客需求重要度评价方法,该方法的最大特点是直接从学习后的网络连接权重中提取出顾客需求重要度信息,讨论了网络的拓扑结构,以及如何从学习后的网络权重中提取出顾客需求重要度信息的方法,应用统计方法消除了网络学习初始权重对最终评估结果的影响,用一案例对提高提出的方法进行了验证,分析了网络隐含层节点数变化对顾客需求重要度评估结果的影响,实验表明,     

Genetic variation increases during biological invasion by a Cuban lizard

A genetic paradox exists in invasion biology: how do introduced populations, whose genetic variation has probably been depleted by population bottlenecks, persist and adapt to new conditions? Lessons from conservation genetics show that reduced genetic variation due to genetic drift and founder effects limits the ability of a population to adapt, and small population size increases the risk of extinction. Nonetheless, many introduced species experiencing these same conditions during initial introductions persist, expand their ranges, evolve rapidly and become invasive. To address this issue, we studied the brown anole, a worldwide invasive lizard. Genetic analyses indicate that at least eight introductions have occurred in Florida from across this lizard's native range, blending genetic variation from different geographic source populations and producing populations that contain substantially more, not less, genetic variation than native populations. Moreover, recently introduced brown anole populations around the world originate from Florida, and some have maintained these elevated levels of genetic variation. Here we show that one key to invasion success may be the occurrence of multiple introductions that transform among-population variation in native ranges to within-population variation in introduced areas. Furthermore, these genetically variable populations may be particularly potent sources for introductions elsewhere. The growing problem of invasive species introductions brings considerable economic and biological costs. If these costs are to be mitigated, a greater understanding of the causes, progression and consequences of biological invasions is needed.     

我国物流企业生产效率发展分析

为分析我国物流企业生产效率的发展状况, 利用DEA CCR模型和Window Analysis技术对我国18家物流企业在2001--2006年间的生产效率进行发展分析.通过分析发现: 1) 我国物流市场缺乏有效的市场淘汰机制,物流企业生产效率的个体差异显著; 2)我国港口经营类企业的平均生产效率高于运输仓储类企业的平均生产效率;3) 我国物流企业整体生产效率水平较低,但在所研究的时间内呈稳定且上升的发展状态.     

我国物流企业全要素生产效率分析

为分析我国物流企业生产效率的发展情况,本文以我国8家上市物流企业为例,利用DEA Malmquist生产效率变化指数对它们在2001～2006年的全要素生产效率进行分析.通过分析发现,我国物流企业的生产效率发展趋势较好,呈上升状态,但上升程度并不明显,其中技术效率和技术有所下滑,而规模效率则有所上升.同时结合了企业组织形式、资源配置及发展战略等内部因素和国内外经济发展环境、国家产业发展政策与法规等外部因素对各个企业和它们的整体生产效率发展过程进行了分析和说明,提出了解决我国物流企业生产效率偏低的途径,为政府决策者和物流企业管理者提供了科学决策的依据.