A nonnegative extension of the affine demand function and equilibrium analysis for multiproduct price competition

We derive a nonnegative extension of the affine demand function for differentiated substitute products from the optimization problem facing a representative consumer whose utility function is quadratic. We show that the extended demand function reduces to a linear program. The linear program has a simple intuitive interpretation in terms of a shifted price vector. We prove the existence and uniqueness of the Bertrand equilibrium in oligopolies consisting of multiproduct firms under the proposed demand function. The equilibrium, available in closed form, coincides with that obtained when allowing negative demands.     

A production–inventory model in an imperfect production process

The paper develops a model to determine the optimal product reliability and production rate that achieves the biggest total integrated profit for an imperfect manufacturing process. The basic assumption of the classical Economic Manufacturing Quantity (EMQ) model is that all manufacturing items are of perfect quality. The assumption is not true in practice. Most of the production system produces perfect and imperfect quality items. In some cases the imperfect quality (non conforming) items are reworked at a cost to restore its quality to the original one. Rework cost may be reduced by improvements in product reliability (i.e., decreasing in product reliability parameter). Lower value of product reliability parameter results in increase development cost of production and also smaller quantity of nonconforming products. The unit production cost is a function of product reliability parameter and production rate. As a result, higher development cost increases unit production cost. The problem of optimal planning work and rework processes belongs to the broad field of production–inventory model which deals with all kinds of reuse processes in supply chains. These processes aim to recover defective product items in such a way that they meet the quality level of ‘good item’. The benefits from imperfect quality items are: regaining the material and value added on defective items and improving the environment protection. In this point of view, a model is introduced here to guide a firm/industry in addressing variable product reliability factor, variable unit production cost and dynamic production rate for time-varying demand. The paper provides an optimal control formulation of the problem and develops necessary and sufficient conditions for optimality of the dynamic variables. In this purpose, the Euler–Lagrange method is used to obtain optimal solutions for product reliability parameter and dynamic production rate. Finally, numerical examples are given to illustrate the proposed model.     

A dynamic rationing policy for continuous-review inventory systems

Stock rationing is an inventory policy that allows differential treatment of customer classes without using separate inventories. In this paper, we propose a dynamic rationing policy for continuous-review inventory systems, which utilizes the information on the status of the outstanding replenishment orders. For both backordering and lost sales environments, we conduct simulation studies to compare the performance of the dynamic policy with the static critical level and the common stock policies and quantify the gain obtained. We propose two new bounds on the optimum dynamic rationing policy that enables us to tell how much of the potential gain the proposed dynamic policy realizes. We discuss the conditions under which stock rationing – both dynamic and static – is beneficial and assess the value of the dynamic policy.     

Triple seasonal methods for short-term electricity demand forecasting

Online short-term load forecasting is needed for the real-time scheduling of electricity generation. Univariate methods have been developed that model the intraweek and intraday seasonal cycles in intraday load data. Three such methods, shown to be competitive in recent empirical studies, are double seasonal ARMA, an adaptation of Holt–Winters exponential smoothing for double seasonality, and another, recently proposed, exponential smoothing method. In multiple years of load data, in addition to intraday and intraweek cycles, an intrayear seasonal cycle is also apparent. We extend the three double seasonal methods in order to accommodate the intrayear seasonal cycle. Using six years of British and French data, we show that for prediction up to a day-ahead the triple seasonal methods outperform the double seasonal methods, and also a univariate neural network approach. Further improvement in accuracy is produced by using a combination of the forecasts from two of the triple seasonal methods.     

供应中断下零售商的最优定价和最优分批订购策略

考虑了由两个可靠性不同的供应商,一个零售商和一个竞争零售商组成的供应链系统,研究了以双垄断市场为背景,在供应中断条件下,建立了零售商的最优定价模型,给出了最优销售价格和分批订购策略.最后通过数值算例就零售商和竞争零售商价格对竞争零售商的采购成本在不中断和中断情形下做了比较.     

非对称信息下的后端VMI协调模型

对VMI模式下的两层供应链,在考虑制造商的生产成本信息对称和不对称两种情形下,运用委托-代理理论设计了基于可转移效用-折扣策略的VMI协调机制,有效地改善了分散式供应链结构下由激励不一致、信息不对称等因素引起的供应链效率低下问题,以达到在提高供应链渠道效益的同时,实现制造商和零售商收益的pareto改进.     

需求不确定性对闭环供应链系统决策的影响分析

在由一个制造商与一个销售商组成的闭环供应链系统中,构建了市场需求不确定环境下废旧产品回收率为外生变量和零售商决策变量两种情形的闭环供应链系统决策模型,并通过数值仿真得到了各模型供应链成员的最优定价和订货策略以及最终利润,进一步分析了两种情形下市场需求不确定性对零售商、制造商决策行为及利润的影响,最后对两种情形进行了对比分析.     

中国房价形成机制的实证研究

构建了房地产市场的供求模型和均衡价格模型,引入商品房销售价格、销售面积、施工面积等9个变量,建立相应的联立方程组,对房地产价格形成机制进行了研究.研究结果表明：房地产的价格很大程度上受到居民收入、利率、以及土地价格的影响,相对而言居民收入和利率的影响最为明显.同时,居民对房地产的潜在需求和有效需求间的差距较大.目前相关部门应更加关注房地产市场有效需求的规模,并适当调整利率、土地供给等,从而保证房地产市场的稳定发展.     

基于时变需求的集成多级供应链生产订货策略研究

考虑一个时变需求环境下集成多级供应链问题,在有限的规划时间内销售商以固定周期订货,而生产商以不同的周期生产,目的是寻找销售商最优的订货周期和生产商最佳的生产策略,从而使供应链系统的总运营成本最少.建立了该问题的混合整数非线性规划模型,求解该模型分为两步：先求对应一个订货周期的最佳生产策略,再求最优的订货周期,第一步用到了图论里求最短路方法.给出了两个步骤的算法和程序,实验证明它们是有效的.通过算例对模型进行了分析,研究了各参数对最优解及最小费用的影响.