Optimal policy with a total order quantity commitment contract in the presence of a spot market

In this paper,the optimal policy is considered when the buyer faces two supply sources:one is the contract supplier from which the buyer orders over a specific contract period(say,a year) at a pre-agreed price,and the other is the spot market.However,when ordering from the contract supplier,the buyer must fulfill a pre-determined total order quantity,or the so-called definite total order quantity commitment,over the whole contract period.In other words,the commitment secures the buyer a fixed price but obliges him/her a total order quantity over the contract period.Although the spot market gives the buyer more flexibility in terms of order quantities,its prices are volatile.Such a combination of contract and spot procurements is often observed in practice.Within the contract period,there are multiple sub-periods,during each of which the buyer reviews the inventory,issues an individual order,and uses the on-hand inventory to meet the random demand.Thus,in each(ordering) period,the buyer will weigh between the current known spot price(by procuring from the spot market) and a lower future price(by waiting while consuming the remaining commitment).An optimal dual ordering policy is characterized for each period,depending on the on-hand inventory level,the spot price,and the remaining commitment quantity.The optimal policy in each period is also shown to be independent of the contract price.Through a numerical study,the inventory cost is demonstrated to be(1) insensitive to the contract price when the total commitment quantity is lower than the total expected demand over the contract period and(2) non-increasing in the variability of spot prices.     

课堂教学方法的研究与实践

课堂教学作为学生获取知识的主战场,如何发挥课堂50分钟教学的作用?让学生在课堂教学中随着教师不同时段教学内容的设计、教学方法的调整,使学生的兴奋点和主要精力集中在一堂课程教学内容的重点与难点上,从而发挥课堂教学的最大效用.笔者提出了将课堂教学分为"5个时段7种方式"的教学模式来达到课堂教学效用的最大化.     

UWB系统中高斯脉冲信号特性的研究

通过对高斯脉冲UWB信号的数学框架研究,得到改变高斯脉冲形成因子和对高斯脉冲进行微分运算可以提高脉冲峰值频率和带宽的结论,由此能够获得理想的UWB脉冲.仿真结果表明,基于高斯脉冲组合可以获得逼近FCC标准的UWB信号,为分析UWB信号传输提供了理论依据.     

双歧杆菌的研究现状

双歧杆菌,肠道内一种有益菌种.本文主要对其调节人体生理功能作用和在食品学方面的应用研究进行了综述,以期为双歧杆菌食品的研究开发提供基础资料.     

长春市高校女生体育课兴趣现状及培养的研究

高校体育是学校体育的最后阶段,是形成终身体育意识的重要时期.学校体育是终身体育的基础,如何在高校体育教学中培养学生的体育意识和兴趣,已经成为体育教育工作者关心的主要问题.对高校女生对体育课兴趣不高的现状及成因进行了分析和研究,并在此基础上系统阐述了解决这一问题的措施和方案,以求为提高高校女生体育课的教学质量提供科学的参考依据.     

英语课堂创新教育的若干思考

论述了英语课堂创新教育中应遵循的基本原则,即民主性原则、开放性原则、主体性原则.作者认为英语教学是一门实践性很强的学科,要与学生换位思考,形成课堂互动.并阐述英语创新教育的教学策略,即扎实的语言知识功底是提高运用英语能力的基石,坚持优化学生合理的能力结构(读、说、听、写).并指出英语教学中应注重对学生健康人格的培养.     

改进液压传动课教学方法培养创新型人才

本文就适应高校培养创新型人才的要求,从长期的教学实践中总结出应用于理论教学中的引导式教学法和精品觅食教学法,对高等学校的教法研究具有借鉴作用.     

八项质量管理原则在高校教育服务中的应用

ISO9001质量管理标准的八项管理原则是质量管理实践经验的高度概况和总结,是质量管理最基本、最适用的一般性规律,它同样可以使用在高等学校的教育服务管理中,是高校更好地为学生服务、为家长和社会服务的指南.     

When horsetails became giants

Horsetails arose in the Late Devonian,evolved a greater diversity and forming fast growing bamboo-like thickets in the Carboniferous lowland swamp forest ecosystems.However,the diversity of this group drastically declined during the Permian while the climate became more dynamic and arid.Today only a single surviving genus exists,the herbaceous Equisetum.Here we report an exceptional large horsetail tree from the Early Permian Petrified Forest of Chemnitz.This fossil horsetail tree is assigned to Arthropitys bistriata (Cotta) Goeppert.It is 15 m high and over 25 cm in diameter,with thick wood and at least 3 orders of woody branching system formed a big canopy,and is morphologically very comparable with the living woody higher plants.This suggests that the plasticity mechanism of Permian calamitaleans enabled novel growth strategies when they competed with the rising gymnosperms during the environmental changes.