易变质产品在带运输时间的二级供应链中的订购策略研究

研究了带运输时间的易变质产品的二级供应链库存模型。在有限计划期内,为补充下游分销商发出的订单,上游制造商以一定的生产速率进行生产。由于产品运输给分销商时需要花费时间与成本,在开始一段时间内分销商的订单得不到及时补充,只有当制造商的库存量达到最大时,才将产品运输给分销商。目标就是确定最优订购策略使得整个系统的总成本最小。通过分析成本函数的特点,证明了2种特殊情形下最优解的存在及唯一性。最后通过算例验证了最优策略的有效性。     

实时交通信息诱导下的出行模式及效益评价

以往针对交通出行信息系统的研究主要集中在静态交通网络上,而很少研究实时出行信息诱导下驾驶员的动态行为反应.该文研究交通信息诱导下驾驶员的动态行为反应和交通网络上的非均衡交通演化,并在此基础上评价了出行信息系统的效益.首先建立了3种情况下的交通出行行为:正常交通情况下驾驶员的路径和出发时间选择行为;交通事故发生后驾驶员在...     

市场信息集聚效应与交易效率的研究

本文从市场交易这个角度来研究信息和效率问题.主要结果,1)提出了市场信息多样化和集聚的概念,并给出了信息集聚的数学表述;2)建立了不完全市场交易的讨价——还价交易谈判动态博弈模型,得到多阶段交易的贝尔曼方程;3)以此证明了市场信息的集聚效应,产生报酬递增和提高市场流动性.这是市场信息更重要的价值和作用机理,而不仅仅是通...     

学习型管理者的过度自信行为对连续并购绩效的影响

以2000-2007年间的1154家上市公司的3578次并购事件为样本,将并购公司管理者分为过度自信学习组和理性学习组,分析它们对上市公司连续并购绩效的影响。结果表明:随着并购次序的上升,当并购公司的管理者过度自信且有学习行为时,并购绩效呈先降后升的U型趋势;当管理者理性且有学习行为时,并购绩效逐渐下降。本文还发现,无论有学习行为的管理者是理性的,还是过度自信的,并购的时间间隔都随着并购次序的上升逐渐下降。     

有模糊时间窗的车辆调度组合干扰管理研究

研究带有模糊时间窗的车辆调度组合干扰管理模型及其混合遗传算法.采用时间窗模糊化处理方法,定义客户满意度函数,根据干扰管理思想对车辆调度中组合性干扰事件进行分析,从配送路径、配送成本和客户满意度三个方面进行干扰辨识与度量,建立基于模糊时间窗的车辆调度组合干扰管理模型;构造模型求解的混合遗传算法,将最佳客户插入规则与遗传算法结合,同时在算法中嵌入模糊优化程序以处理问题的模糊特征;进行数值实验,实验结果验证了模型与算法的有效性.     

基于符号时间序列方法的金融收益分析与预测

引入符号时间序列分析方法从大尺度的角度分析收益变化的特征,提出了确定收益变化的主要模式并预测收益水平的方法。首先将收益序列转化为符号序列,由符号序列中不同的字代表不同的收益变化模式,根据符号序列直方图,可以确定收益变化的主要模式。然后,根据各收益变化模式的概率分布,在前几个时点收益水平确定的情况下,可以推知下一个或几个时点处于不同收益水平的概率,从而实现对收益水平的预测。对上证综指、深证成指以及上证工业股指数、上证商业股指数、上证地产股指数、上证公用事业股指数共六个股票指数的收益序列进行了实证分析,确定了各指数收益的主要变化模式,并基于主要变化模式进行了收益水平的预测,从而说明了该方法的有效性和可行性。     

How Excessive Stage Time Reduction in NPD Negatively Impacts Market Value

We empirically investigate how time reductions in particular product development stages impact market value. Using longitudinal project data from 107 firms, we compare stage times prior to and following investments in new product development process changes. Our analysis reveals a predominance of focus on time reduction in the late stages of product development. We also find support for the existence of an inverted‐U relationship between market performance and time reductions for some of these stages: beta testing and technical implementation. Therefore, while time reductions can improve time to market, we observe a clear limit to the benefits associated with stage time reductions at particular stages. We also investigate the role of strategic contextual factors such as the extent to which a firm's patented innovations rely upon a variety, as opposed to a limited range, of diverse technology classes. The extent of this technology‐span impacts optimal stage time reductions. We perform an in‐depth post hoc analysis with a small set of firms to uncover how they should invest in stage time reduction given our empirical results. The post hoc analysis highlights that some firms are likely overinvesting in stage time reductions and destroying market value.     

From Bottom of the Barrel to Cream of the Crop: Sequential Screening With Positive Selection

In a number of interesting environments, dynamic screening involves positive selection: in contrast with Coasian dynamics, only the most motivated remain over time. The paper provides conditions under which the principal's commitment optimum is time consistent and uses this result to derive testable predictions under permanent or transient shocks. It also identifies environments in which time consistency does not hold despite positive selection, and yet simple equilibrium characterizations can be obtained.     

Assessing Risk in Graphically Presented Financial Series

It has been argued that traders use their natural sensitivity to the fractal properties of price graphs to assess risk and that they are better able to do this when given price change as well as price level information. This approach implies that risk assessments should be higher when the Hurst exponents are lower, that this relationship should be stronger in the presence of price change information and that risk assessment should depend more strongly on the Hurst exponent than on the standard deviation of the series. Participants in Experiment 1 decided which of two assets was riskier by inspecting graphs of their price series. Graphs with lower Hurst exponents were selected only by those who were less emotionally stable and hence more sensitive to risk. However, when both price series and price change series were presented, the assets with lower Hurst exponents were selected by all participants. In a second experiment, participants were given both price level and price change series for a number of assets and rated the risk of trading in each one. Ratings depended more strongly on Hurst exponents than on other measures of volatility. They also depended on indicators of potential loss. Human risk assessment deviates from the way that risk is measured in modern finance theory: it requires integration of information relevant to both uncertainty and loss aversion, thereby imposing high attentional demands on traders. These demands may impair risk assessment but they can be eased by adding displays of price change information.     

现代汉语习惯体分析

文章介绍了围绕着习惯体的类型学争论,具体分析了汉语中习惯体的表达方法和时间指涉特点,在此基础上进一步分析了习惯体和非现实原型的相似度,认为汉语中存在习惯体并且比较接近非现实范畴。