非对称成本扰动信息下双渠道供应链的契约设计

研究由单制造商和单零售商组成的双渠道供应链系统在非对称的生产成本扰动信息下的契约设计问题.使用委托代理理论,通过求解零售商优化问题的Kuhn-Tucker条件,给出了非对称的生产成本扰动信息下的双渠道供应链的最优契约,并且分析了非对称成本扰动信息对于双渠道供应链定价决策、生产数量决策及供应链成员利润和整个系统性能的影响.研究表明,当生产成本扰动满足一定条件时,初始的生产计划仍然是最优的;制造商私有成本扰动信息不一定会给系统带来利润损失,并且明确给出了未造成利润损失的边界条件.     

需求与退货价格具有相关性的双渠道供应链模型与协调

考虑由单个制造商和单个零售商组成的双渠道供应链,制造商负责产品的生产,生产出来的产品一部分由零售商进行传统渠道销售,另一部分由制造商通过网络进行直销.传统零售渠道和网络直销渠道都为消费者提供退货服务,且退货价格与两个渠道的市场需求具有相关性.通过建立双渠道供应链博弈模型,分析了集中式决策和分散式决策下的退货价格策略,并就两种决策模式下的退货策略进行了比较分析,同时就双渠道供应链实现协调进行了合同设计.研究表明:在批发价格契约下不能实现双渠道供应链的协调,而采用两部定价合同可实现双渠道供应链的协调.     

需求均匀分布条件下考虑零售商销售努力的双渠道供应链协调

针对单个制造商和单个零售商组成的双渠道供应链,零售商面对的需求为均匀分布市场,且需求与零售商销售努力及双渠道销售价格具有相关性.通过建立双渠道供应链模型,分析了集中式决策下双渠道供应链的销售努力、零售价格、直销价格及订货量策略,给出了双渠道供应链协调的条件.研究结果表明:采用回馈与惩罚契约及回购契约的双契约组合不能有效协调双渠道供应链,而在此基础上加入收益分享策略能够实现双渠道供应链协调.最后,通过数值计算对结果进行了验证.     

零售商风险规避下差异化渠道的三层供应链协调

考虑市场需求不确定时零售商的风险规避问题,研究在制造商主导的三层单渠道分销的供应链中零售商的最优订购策略、分销商的定价均衡和制造商的定价策略.然后增加一个提供回购契约的分销商,研究在零售商双重采购和制造商差异化双渠道分销的三层供应链中风险规避型零售商的最优订购策略、两个相互竞争的分销商和制造商的定价策略.通过决策对比分析,建立基于差异化双重分销渠道的三层供应链的协调机制.研究结果表明,与单渠道供应链相比,差异化双重分销渠道的形成可以使供应链成员的收益均得到增加,实现供应链的帕累托改进,且帕累托区域的位置与范围受到零售商风险规避程度的影响.     

制造商资金约束下的双渠道供应链协调

考虑由单一零售商和受资金约束的单一制造商组成的双渠道供应链,在引入带有价格折扣因子的零售商提前付款融资模式时,如何实现协调的问题.在制造商主导的Stackelberg博弈下,研究了制造商和零售商之间的库存协调问题,并建立了使得双渠道供应链实现协调的收入共享契约模型.给出了供应链协调时契约参数满足的表达式,并分析了价格折扣因子、初始资金对供应链及其成员的影响.最后,通过算例验证了契约对双渠道供应链协调的有效性及相关参数的作用.     

零售商竞争下基于CVaR与收益共享契约的供应链决策模型

针对随机需求与零售商价格竞争相关,基于收益共享契约,研究一个风险中性的制造商和两个风险规避型零售商组成的供应链.通过指数乘法需求形式将价格竞争引入到需求模型中,并以CVaR作为零售商的风险度量准则,证明了竞争的零售商存在唯一最优的定价-订购联合决策,并给出了具体的解析表达式.借助于理论推导和数值分析,给出零售商的价格竞争和风险规避对供应链成员最优决策和渠道效率的影响.结果表明,收益共享契约不能完美协调此类供应链,零售商竞争有助于改善渠道效率,而零售商的风险规避降低渠道效率.     

混合需求下双渠道供应链联合定价决策与协调机制研究

文章考虑了同时面临确定需求和随机需求的双渠道供应链的最优决策和协调问题,研究表明价格博弈的纳什均衡解存在;并给出了能使制造商和零售商完美协调的简单易行的机制——制造商指导定价契约,通过算例验证了该契约能实现完美协调,并从分布函数形式及不确定性大小等角度分析了其中规律。     

非对称信息下双渠道供应链应对突发事件协调模型

针对由制造商主导的双渠道供应链,引入双渠道价格敏感系数及竞争系数两个变量,假设零售商的成本信息为私有条件,研究在非对称信息下发生突发事件的双渠道供应链最优应对。研究结果表明,供应链的最优生产量、最优直销价格、批发价格和最优零售价格具有一定的鲁棒性。在非对称情形下,突发事件导致零售商成本在一定范围内扰动时,双渠道供应链的最优生产计划、销售计划可以保持不变。但当零售商的成本扰动超出了一定范围时,则需要通过协调才能使供应链重新达到平衡,实现对突发事件的有效应对。最后,通过数值仿真验证了研究结果。     

应急环境和非对称信息下两个竞争零售商的供应链批发价契约

研究了非对称信息下包含一个供应商和两个Bertrand竞争零售商的两级供应链系统批发价契约如何应对突发事件问题.首先在正常状态下,当零售商成本信息为非对称信息时,设计了集中控制下供应链契约和分散控制下供应链批发价契约.当突发事件造成零售商的成本分布变化时,给出了上述两种供应链契约的应急决策.仿真结果表明,当零售商成本扰动在一个很小范围内时,供应商可以保持原生产计划不变,说明原有的契约机制具有一定的鲁棒性;当扰动比较大时,要对原来的生产计划进行调整.     

政府补贴和消费者绿色偏好供应链策略及协调

在考虑政府补贴和消费者绿色偏好情形下,为探究制造商开通在线渠道的动机,以及不同渠道 结构中供应链成员最优决策和社会福利的变化,构建制造商领导、零售商跟随的 Stackelberg 模型;比较不同 渠道结构下供应链成员的均衡策略,并设计价格折扣和成本分担契约实现供应链协调,最后通过算例对模型 进行验证;研究发现,政府补贴能够提高制造商开通在线渠道的动机;与单渠道相比,双渠道结构能够明显提 高制造商的利润及社会福利;零售商双渠道的利润是否高于单渠道的利润与消费者绿色偏好有关,当消费者 绿色偏好较高时,零售商双渠道的利润才高于单渠道的利润;价格折扣和成本分担契约可以实现整个供应链 系统协调,并且政府补贴和消费者绿色偏好越高时,供应链整体利润改进的幅度越大,此时制造商和零售商 更有合作的意向。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Features of Women''s language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

英文诗歌中的喻类修辞

为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。     

Man Is Unable to Change the Miserable Life——Analysis of the Arrangement of Four Characters in The Glass Menagerie

Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.     

Characterization of root-nodulating bacteria on Retama raetam in arid Tunisian soils

The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme