模糊环境下零售商竞争的供应链协调研究

本文对模糊环境下两个竞争零售商供应链系统的最优决策及协调问题进行了研究。首先分析比较了在一体化决策和分散化决策下受模糊变量影响的两竞争零售商的最优决策,然后提出了收益共享契约协调模型,并通过模型求解得到了收益共享契约成立的条件,结果表明收益共享契约成立不仅与收益参数有关,还与生产成本c、需求价格弹性系数βi(i=1,2)和市场规模ai(i=1,2)的期望值以及生产成本c和竞争对手需求价格弹性β2的乐悲观值有关。最后通过数值实验分析了收益参数及模糊变量取值对收益共享契约模型中供应链系统各成员期望利润的影响。     

基于微分对策的绿色供应链生态研发策略与协调机制

综合考虑产品绿色度和价格对市场需求的多重影响,构建微分博弈模型,运用最优控制理论,先后考察并比较批发价契约、收益共享契约和集中式决策三种情形下绿色供应链最优生态研发努力和定价策略,进一步采用Rubinstein讨价还价模型设计合理的利润分配契约。研究发现:收益共享契约无法促使绿色供应链实现协调,但在一定条件下,能够有效消除批发价契约的“双重边际效应”;集中式决策下,合理的利润分配契约能够保证供应链成员分得的利润“帕累托最优”,实现供应链协调,且该契约与收益共享比例有关。     

风险厌恶下的供应链收益共享契约协调模型研究

收益共享契约是实现供应链系统绩效改善或完美协调的一种机制.考虑了零售商与供应商分别具有风险厌恶决策偏好情况下,在随机市场需求下建立了由单供应商和单零售商组成的二级供应链的收益共享契约模型,并对模型进行了分析,揭示了供应商和零售商的风险厌恶决策偏好对收益共享契约参数的影响.研究结果表明:当销售商(供应商)的风险厌恶控制在...     

模糊需求环境下的三级供应链协调机制研究

研究一个由供应商、分销商和零售商组成的三级供应链系统在模糊需求环境下的协调机制。需求函数中的参数视为三角模糊数，分析模糊环境下的分散决策和集中决策过程，给出收益共享契约机制下的决策模型。最后通过一个数值分析表明，在模糊需求环境下，收益共享契约机制同样可以实现供应链中各成员间的协调。     

不利天气影响下考虑农户公平关切的农产品供应链协调机制研究

在不利天气影响农户努力水平和农产品产量的情况下,考虑农户公平关切,建立公司主导的二级农产品供应链Stackelberg模型,分析农户公平关切对农户努力水平、公司收购价格以及农产品供应链协调性的影响.研究表明:无论农户是否公平关切,“保底收购,随行就市”的订单价格机制都无法实现农产品供应链协调,且农户公平关切会进一步使农产品供应链利润偏离最优.其次,收益共享契约总能实现集中决策下最优努力水平、最优农产品供应链利润,提高农户利润,但会使公司利润降低,导致农产品供应链稳定性降低.最后,“收益共享+加盟金”组合契约不仅能实现集中决策下最优努力水平、最优农产品供应链利润,实现农产品供应链协调,还能帕累托改进农产品供应链各成员利润,提高农产品供应链稳定性.     

考虑差别定价的闭环供应链协调应对突发事件研究

本文以一个新产品和再造品存在差别定价的零售商负责回收闭环供应链为研究对象,研究突发事件干扰下如何采用收益共享契约协调分散式决策闭环供应链的问题。首先,给出了一个可协调稳定环境下分散式决策闭环供应链的收益共享契约;其次,在突发事件同时干扰闭环供应链中新产品和再造品最大市场需求规模的情况下,分析了集中式决策闭环供应链的最优应对策略,并证实了原收益共享契约在突发事件干扰下会失效;最后,通过对原收益共享契约进行改进,解决了突发事件干扰下的分散式决策闭环供应链协调问题,且改进后的收益共享契约也能够协调稳定环境下的分散式决策闭环供应链。     

基于历史强度法的闭环供应链差别定价与协调

针对由一个制造商与一个零售商组成的闭环供应链,基于历史强度法分配企业碳排放配额,分别构建分散决策与集中决策下成员及系统利润最大化模型,得到新品与再制造品的定价、碳减排投资等决策,分析了行业控排系数对产品碳减排量、定价及市场需求的影响,并对两种决策结构进行比较和收益共享契约设计.研究表明,提高行业控排系数有助于增加碳减排投资、降低单位产品碳排放量、扩大新品与再制造品需求、推动废旧品回收再制造和供应链总利润提升;从最大化系统利润和降低单位产品碳排放角度,集中决策比分散决策要好;但从决策效果看,采用协调机制下的收益共享契约最好.     

非对称信息和模糊需求下的闭环供应链协调决策研究

在模糊需求和非对称销售价格信息下,研究了由单一制造商和零售商组成的两级闭环供应链系统的协调问题。通过建立不确定环境下的集中决策和收益共享-费用共担契约决策模型,分别得到了不同模型下闭环供应链系统的最优策略。并进一步通过算例分析了契约下供应链各方收益随模糊需求和价格的变化情况,以及该契约对整个系统决策效率的影响。结果表明:收益共享-费用共担契约能有效实现模糊闭环供应链系统的协调,实现闭环供应链系统决策的最优化;其次,需求和零售价格的不确定性程度越高,对零售商的最优订购量、供应链成员及系统利润的影响也越大。     

资金成本下延迟支付期限的收益分享契约

针对由单一制造商和单一零售商组成的供应链系统,建立了随机需求下考虑有资金成本延迟支付期限的收益分享契约模型,研究两种决策(分散化和集中化)下,延迟支付期限是如何影响资金约束零售商的最优订货数量以及供应链系统的利润.分析表明,不管是分散化还是集中化决策,考虑有资金成本延迟支付期限的收益分享契约使供应链系统的最优订货量和利润都增大.最后,运用数值分析验证了结论.     

基于商业信用的收入共享契约与供应链协调

在一个供应商和一个零售商构成的供应链中,由于供应商向零售商提供商业信用,订货量和资金占用的变化会影响供应商与零售商各自的利润.为了确定公平合理的收益分配机制,建立了随机需求下基于商业信用的收入共享契约协调模型,分析了商业信用条件下收入共享机制在实现收益的合理分配与改进供应链整体运作绩效方面的作用,推导出实现分散供应链协调的最优契约参数.最后通过数值算例说明了所得结论.     

Filling in solvable groups and in lattices in semisimple groups

We prove that the filling order is quadratic for a large class of solvable groups and asymptotically quadratic for all -rank one lattices in semisimple groups of -rank at least 3. As a byproduct of auxiliary results we give a shorter proof of the theorem on the nondistorsion of horospheres providing also an estimate of a nondistorsion constant.     

Introducing technology in algebra in Hong Kong: addressing issues in learning

A review of recent studies in Hong Kong suggests that possible problems in secondary school algebra may be due to the procedural paradigm orientation in the curriculum and the conventional style of teaching in the classroom which do not provide sufficient opportunities for students to develop conceptual understanding. Based on the works of a number of projects in the West, it is hypothesized that the introduction of technology in lessons which embody a cognitive model in their design and delivery will provide a viable alternative for enhancing algebraic thinking. The key features of the cognitive model are concrete preparation, cognitive conflict, construction, metacognition and bridging, imbedded in a ‘mediation’ style of teaching. These features are exemplified by detailed accounts of classroom episodes from a Hong Kong lesson supported by the use of graphics calculators. Results indicate that while the approach places particular demands on teachers (a tension between a transmission style of teaching and mediating) there is real potential for supporting more dynamic student constructions.     

抓好数学建模竞赛 推动数学教学改革

本文通过近几年组织数学建模教学和指导学生参加竞赛的实践 ,探索抓好数学建模竞赛 ,促进数学教学改革 ,推动数学素质教育 ,提高人才培养质量的途径、措施和方法     

Equality in Distribution in a Convex Ordering Family

Let F and G be the respective distributions of nonnegative random variables X and Y satisfying the convex ordering. We investigate the class of functions h for which the equality E[h(X)] = E[h(Y)] guarantees F = G. It leads to extensions of some existing results and at the same time offers a somewhat simpler proof.     

Nonlinear problems arising in electrostatic actuation in MEMS

In this paper we study the nonlinear problem arising in electrostatic actuation of MEMS. We show that the existence and non-existence of the solution of this problem depend on the value of the physical parameters of the equation. In addition we consider the corresponding initial value problem and we derived the existence of periodic solution, stability of steady states and the ω-limit set.     

Testing linear hypotheses in errors in variables model

A multivariate errors-in-variables model in the matrix form can be written as X=U+E, Y=UA+WB+F, where X (n×p) and Y (n×q) are observed matrices, E and F are error matrices whose rows are normally distributed, W (n×k) is a known matrix of rank k, and U, A and B are unknown matrices. We consider the problems of testing linear hypotheses: (i) H ₀: AR=K and (ii) H ₀: SA=L, where R, K, S and L are known matrices, and we derive the likelihood ratio tests for testing these hypotheses.     

Flows in networks with delay in the vertices

Our goal is to show asynchronous exponential growth (AEG) for a flow in a network with delay in the vertices. For this purpose we show first that its wellposedness can be characterized via an appropriate operator being the generator of a strongly continuous semigroup. We investigate the long term behavior of the system via the spectrum of this generator using techniques from operator matrices, Hille‐Yosida operators and positive semigroups. Finally, we apply our results to deduce that our problem has (AEG).     

Testing Homogeneity in Weibull Error in Variables Models

We discuss properties of the score statistics for testing the null hypothesis of homogeneity in a Weibull mixing model in which the group effect is modelled as a random variable and some of the covariates are measured with error. The statistics proposed are based on the corrected score approach and they require estimation only under the conventional Weibull model with measurement errors and does not require that the distribution of the random effect be specified. The results in this paper extend results in Gimenez, Bolfarine, and Colosimo (Annals of the Institute of Statistical Mathematics, 52, 698–711, 2000) for the case of independent Weibull models. A simulation study is provided. An erratum to this article can be found at