移动Adhoc网络中改进的动态源路由算法研究

实时多媒体业务的普及使得提供QoS保证成为移动自组网研究的热点问题。然而移动节点的自由移动和拓扑动态变化,经常造成已经建立的路径断开而需重构路由,造成通信中断和较大的时延与抖动。该文提出了一种改进的动态源路由协议,采用链路状态探测的方法,找到一条最稳定的路径并在通信过程中实时监测路径状态变化,及时进行软切换,有效降低通信中断的概率,从而提供服务质量保证。     

供应链设计中供应商的评价与选择

供应商的评价与选择是供应链设计的关键,直接关系到供应链的竞争力。对一般制造企业中现行选择供应商的方法进行了改进,在原有定性评估的基础上,引进定量评价方法。定量方法采用简单易行的灰关联分析算法,避免了其他方法主观性强、分析精度不高的缺陷;定性方法是企业多年经验的结晶,能够弥补定量方法的不足,具有独特的优势。定量和定性方法相辅相成,可确保选择供应商的方法合理与准确。     

论家族企业传承的途径选择

本文分析了我国家族企业传承问题的现状,通过家族企业各阶段的不同特征来分析三种传承途径的利弊,为家族制企业初创阶段、发展阶段、成熟阶段的传承进行了深入论证,从而推出选择家族成员接班、内部提升任用、引进职业经理人等三种模式。     

技术变迁对城市化路径的作用机制研究

从城市化的一般机理入手,对城市跟农村技术进步以及二者之间的技术转移对城市化的作用机制进行了研究。比较城市化实际路径与均衡路径的区别,论证了技术变迁对城市化质量的决定性作用。     

门店选址对大型综合超市经营绩效的影响分析

本文从大型综合超市的特点及其对门店选址的要求出发，分析了门店选址对大型综合超市所产生的收入性和成本性双重影响。就收入性影响而言，门店选址的好坏对大型综合超市的客流量、商品组合及商品档次等将产生直接的影响；就成本性影响来说，门店选址将从租金、宣传费、管理成本等方面产生直接的影响。因此，大型综合超市的选址应注重自身特性并关注其影响经营效绩的各个方面。     

Simulated real-time detection of multiple structural changes: Evidence from Japanese economic growth

An efficient treatment of practical issues on detecting multiple structural changes is presented. The efficacy of this method is examined by comparing the conventional hypothesis-testing method via comprehensive simulations and empirical applications. The method recommended is a model-selection using the Bayesian information criterion and allowing for heteroscedasticity. Empirical results show that the first structural change of Japanese economic growth occurred in 1974Q2, which was detected in 1979Q4, and that the second structural change occurred in 1992Q2, which was detected in 1998Q1. Two advantages of the model-selection method compared to the hypothesis-testing method are also discussed.     

马钢二钢轧总厂低碳易拉丝钢1008的生产实践

结合马钢二钢轧总厂的工艺装备水平,介绍低碳易拉丝钢1008的生产操作实践;详尽分析了该钢种的冶炼、精炼、连铸、轧制工艺及质量控制水平情况.     

“买断工龄”的成因与后果——一个信息经济学分析

随着我国国有企业市场化改革的发展,一些运营困难的企业对内部职工实施了"买断工龄"的政策。在前人研究的基础上,从信息经济学的角度,对"买断工龄"产生的根本原因及后果进行量化分析,具有一定的理论和实践意义。     

What can Statistics Contribute to a Causal Understanding?

Abstract.  We discuss the concept of causality in a broad manner. The traditional attitude in statistics has been to shy away from the causality concept. In recent years, however, a more proactive attitude to the causality concept has developed among statisticians. On the one hand, there is the school of counterfactual causality directed towards forming a better basis for clinical trials and epidemiology. On the other hand, there is the mechanistic view of causality. These developments are discussed and set into a larger context, where the often ignored role of time is emphasized. An extension of path analysis to stochastic processes is briefly presented. Causality is furthermore discussed in relation to genetic studies and to the emerging field of systems biology. Statisticians should also relate to the philosophical content of causality, especially that found in the foundations of physics.     

Variable selection for first‐order Poisson integer‐valued autoregressive model with covariables

In recent years, modelling count data has become one of the most important and popular topics in time‐series analysis. At the same time, variable selection methods have become widely used in many fields as an effective statistical modelling tool. In this paper, we consider using a variable selection method to solve a modelling problem regarding the first‐order Poisson integer‐valued autoregressive (PINAR(1)) model with covariables. The PINAR(1) model with covariables is widely used in many areas because of its practicality. When using this model to deal with practical problems, multiple covariables are added to the model because it is impossible to know in advance which covariables will affect the results. But the inclusion of some insignificant covariables is almost impossible to avoid. Unfortunately, the usual estimation method is not adequate for the task of deleting the insignificant covariables that cause statistical inferences to become biased. To overcome this defect, we propose a penalised conditional least squares (PCLS) method, which can consistently select the true model. The PCLS estimator is also provided and its asymptotic properties are established. Simulation studies demonstrate that the PCLS method is effective for estimation and variable selection. One practical example is also presented to illustrate the practicability of the PCLS method.