用线性互补及二次规划理论分析市场均衡问题

本文讨论了一类完全竞争条件下的市场均衡问题,供给方的生产特征用线性规划模型进行刻划,市场需求函数源于一般经济意义下的模型,它是一系列相互独立的价格变量的函数．我们将此问题归结为线性互补问题,并依此讨论了均衡点的存在性．本文还讨论了一种用二次规划进行刻划的经济问题,并指出此二次规划的K－K－T条件等价于所讨论的线性互补问题．     

The web proxy location problem in general tree of rings networks

The Web proxy location problem in general networks is an NP-hard problem. In this paper, we study the problem in networks showing a general tree of rings topology. We improve the results of the tree case in literature and get an exact algorithm with time complexity O(nhk), where n is the number of nodes in the tree, h is the height of the tree (the server is in the root of the tree), and k is the number of web proxies to be placed in the net. For the case of networks with a general tree of rings topology we present an exact algorithm with O(kn ²) time complexity.This research has been supported by NSF of China (No. 10371028) and the Educational Department grant of Zhejiang Province (No. 20030622).     

两阶段供应链中三种定价方式研究

本文考虑渠道一体化对品牌建设的作用,在一个制造商和两个零售商的两阶段供应链系统中,其中确定性的市场需求与产品的市场零售价格有关,通过分析以下三种定价方式下的最优定价和库存策略下供应链成员和系统的收益,1)商品市场零售价格由零售商各自决定,两零售商和制造商之间存在着竞争活动;2)商品市场零售价格由制造商统一制定;3)市场零售价格、转让价格和系统库存水平按渠道协调的最优原则确定,确定了同一产品品牌内部的市场竞争、定价控制权及转让价格对渠道性能及品牌自身造成的影响,并由此提出了分散决策系统中的一种激励机制.     

动态车辆路径问题排队模型分析

分析了一类动态车辆路径问题,其中顾客需求以泊松流形式出现,现场服务时间服从一般分布.提出解决该问题的两种策略:顺序服务策略和中点改进策略,利用排队论、几何概率论等领域的知识分别求出了这两种策略的系统时间,并通过仿真数据实验验证了这两种策略的有效性.     

带有快速反应策略供应链系统的补偿策略研究

过长的订购提前期往往使得零售商订货决策感到困难. 快速反应策略能使零售商在获 得更多更准确的市场需求信息后,调整订购量而提高收益. 但是快速反应策略并不一定使供应 商的利润也提高. 有文章指出只有低的服务水平才能使两者利润同时提高,因而这种方法在工 业应用中是不一定可行的. 补偿策略是一种广泛应用的方法,能够提高产品的客户服务水平, 因而研究了补偿策略在快速反应供应链系统中的作用. 在某些条件下,在快速反应供应链系统 中,补偿策略能使零售商与供应商一方的收益不变或者提高,另一方的收益有所提高,即Pare2 to 提高. 还研究了引进补偿策略后,供应链系统的最优解及期望卖出量、期望缺货量和期望残 余量的变化情况.     

Problem‐ and solution‐focused characteristics of parenting support, 3 years after implementation of the solution‐focused approach: A qualitative content analysis

In recent years, solution‐focused parenting support has been developed and implemented as a promising brief and strength‐based approach. Given the fundamental differences between solution‐focused and the historically more common problem‐focused parenting support and the complexity of transforming professional practice, an actual shift towards solution‐focused parenting support can be expected to be limited up to now. However, because research into the specific communication characteristics of professional parenting support is currently lacking, no conclusion can be drawn at present. Therefore, this study aims to explore the current problem‐ and solution‐focused characteristics of parenting support in the Dutch youth healthcare (YH). In total, 15 support sessions performed by 10 public health nurses were audio recorded and transcribed verbatim. A detailed qualitative content analysis of professional communication was conducted to identify problem‐ and solution‐focused factual, expressive, relational and appealing aspects of parenting support. Problem‐focused characteristics dominated all sessions of parenting support. This study is the first to thoroughly analyse the problem‐focused and solution‐focused communication characteristics of professional parenting support using a qualitative content analysis. Parenting support practice in the Dutch YH did not shift substantially to a solution‐focused approach. More effort is required to stimulate and facilitate this professional transformation.     

Sensitivity,uncertainty, and decision analyses in the prioritization of research

The evaluation of hazards from complex, large scale, technologically advanced systems often requires the construction of computer implemented mathematical models. These models are used to evaluate the safety of the systems and to evaluate the consequences of modifications to the systems. These evaluations, however, are normally surrounded by significant uncertainties related to the uncertainty inherent in natural phenomena such as the weather and those related to uncertainties in the parameters and models used in the evaluation.

Another use of these models is to evaluate strategies for improving information used in the modeling process itself. While sensitivity analysis is useful in defining variables in the model that are important, uncertainty analysis provides a tool for assessing the importance of uncertainty about these variables. A third complementary technique, is decision analysis. It provides a methodology for explicitly evaluating and ranking potential improvements to the model. Its use in the development of information gathering strategies for a nuclear waste repository are discussed in this paper.     

Generalised Rank Regression Estimator with Standard Error Adjusted Lasso

One of the standard variable selection procedures in multiple linear regression is to use a penalisation technique in least‐squares (LS) analysis. In this setting, many different types of penalties have been introduced to achieve variable selection. It is well known that LS analysis is sensitive to outliers, and consequently outliers can present serious problems for the classical variable selection procedures. Since rank‐based procedures have desirable robustness properties compared to LS procedures, we propose a rank‐based adaptive lasso‐type penalised regression estimator and a corresponding variable selection procedure for linear regression models. The proposed estimator and variable selection procedure are robust against outliers in both response and predictor space. Furthermore, since rank regression can yield unstable estimators in the presence of multicollinearity, in order to provide inference that is robust against multicollinearity, we adjust the penalty term in the adaptive lasso function by incorporating the standard errors of the rank estimator. The theoretical properties of the proposed procedures are established and their performances are investigated by means of simulations. Finally, the estimator and variable selection procedure are applied to the Plasma Beta‐Carotene Level data set.     

An access network design problem with end-to-end QoS constraints

In this paper, we present an access network design problem with end-to-end quality of service (QoS) requirement. The problem can be conceptualized as a two-level hierarchical location-allocation problem on the tree topology with nonlinear side constraints. The objective function of the nonlinear mixed integer programming model minimizes the total cost of switch and fiber cable, while satisfying demand within the prescribed level of QoS. By exploiting the inherent structure of the nonlinear QoS constraints, we develop linearization techniques for finding an optimal solution. Also, we devise an effective exact optimal algorithm within the context of disjunctive constraint generation. We present promising computational results that demonstrate the effectiveness of the proposed solution procedure.     

对旅行社往来款项管理的问题及对策的探讨

往来款项是公司与客户之间的业务往来所形成的款项。在市场信用危机存在的情况下这种方式却导致企业相互间账款的拖欠现象越来越严重，造成企业往来款项负担增加，资金周转困难，影响到公司的正常经营。为此我们应积极寻求新的理念，及时解决往来款项中存在的问题，促进企业积极正常发展。所以，本文分析了中小型旅行社往来款项的问题，针对存在的问题提出相应的改进对策。