一类新型批处理机调度问题的理论分析

钢卷在冷轧生产中,为了改进其性能,需要在罩式炉进行退火,退火过程由加热、保温和降温三段组成,而这三段处理时间由于工艺上的要求不能归结为一个时间,这与传统批处理机调度有明显的差别.对新型批处理机的总加权完成时间最小化问题建立了非线性整数规划模型,开发了基于动态规划的启发式算法.通过理论分析,获得该算法的误差性能比为3.对于三段中的某一段板卷的处理时间相同的情况,证明了启发式算法的误差性能比是2,而且证明是紧界.对于三段中的某二段板卷的处理时间相同的情况,证明了启发式算法是最优算法.对启发式算法扩展到带有任意段的加工时间的一般情况进行了性能分析.     

Lead Time and Price Quotation Mode Selection: Uniform or Differentiated?

Firms in service and make‐to‐order manufacturing industries often quote lead times and prices to customers. We define uniform quotation mode (UQM) as the strategy where a firm offers a single lead time and price quotation, and differentiated quotation mode (DQM) is where a firm offers a menu of lead times and prices for customers to choose from. Both modes are followed in practice. Firms should determine which is more profitable. We classify customers into two groups: lead time sensitive (LS) and price sensitive (PS). LS customers value lead time reduction more than PS customers. We develop mathematical models of both quotation modes and analyze them to determine the most profitable mode under specified situations as well as the best lead time and price quotations within each mode. We find that DQM is dominated by UQM whenever PS customers have positive utilities from UQM or LS customers have positive utilities from DQM. Otherwise, which quotation mode is better depends on multiple factors, such as customer characteristics (including lead time reduction valuation and product valuation of a customer, and the proportion of LS customers) and production characteristics (including the desired service level and service or production cost).     

Container Scheduling: Complexity and Algorithms

We consider the transport of containers through a fleet of ships. Each ship has a capacity constraint limiting the total number of containers it can carry and each ship visits a given set of ports following a predetermined route. Each container has a release date at its origination port, and a due date at its destination port. A container has a size 1 or size 2; size 1 represents a 1 TEU (20‐foot equivalent unit) and size 2 represents 2 TEUs. The delivery time of a container is defined as the time when the ship that carries the container arrives at its destination port. We consider the problem of minimizing the maximum tardiness over all containers. We consider three scenarios with regard to the routes of the ships, namely, the ships having (i) identical, (ii) nested, and (iii) arbitrary routes. For each scenario, we consider different settings for origination ports, release dates, sizes of containers, and number of ports; we determine the computational complexity of various cases. We also provide a simple heuristic for some cases, with its worst case analysis. Finally, we discuss the relationship of our problems with other scheduling problems that are known to be open.     

人民币实际有效汇率变动对中国就业的影响——基于不同层面的实证分析

作为开放经济的核心变量之一,汇率在一国国民经济和对外经济关系中具有举足轻重的作用,它可以通过对外贸易和外商直接投资等渠道对一国就业产生影响。利用1995—2010年我国总体情况,以及16个行业和29个省市的年度数据,采用不同模型就人民币实际有效汇率变动对我国不同层面就业的影响进行的实证分析表明,人民币实际有效汇率上升,无论是对我国就业总量,还是对行业就业或者省市就业的影响都是负向的,即人民币实际有效汇率升值不利于我国各个层面的就业。     

不确定条件下的IT外包时机选择问题研究

IT外包的业务环境、技术环境和需求的不确定性往往会引起IT服务成本的不确定性。针对IT服务成本的不确定性和IT外包投资的不可逆性,运用传统净现值方法和实物期权方法比较固定价格合同、成本加成定价合同和收益共享合同3种常见合同的外包临界值,分析3种合同下客户企业的等待价值,并讨论客户企业推迟外包情形时的等待时间。研究结果表明,实物期权方法得出的外包临界值高于净现值方法得出的外包临界值;等待价值随无风险利率的增大而减小,随漂移率、变动率的增大而增大;当漂移率与变动率平方的比值大于二分之一时,客户企业选择外包的期望等待时间受无风险利率、漂移率和变动率的影响,其他情形下客户企业的期望等待时间不受无风险利率、漂移率和变动率的影响。研究结论为不确定条件下客户企业外包与否和外包时机的选择提供理论支持和实践指导。     

精益生产组成要素之间的关系研究

基于资源基础理论探讨精益生产组成要素之间的关系,并以华南地区118家制造企业为研究样本进行实证研究。研究结果表明:员工参与正向影响TQM/TPM,但对JIT的实施并没有直接的影响,需要通过TQM/TPM间接影响;TQM正向影响TPM的实施;TQM、TPM正向影响JIT,且TQM通过TPM间接影响JIT。研究结论对精益生产的相关理论和实践都有重要的价值和意义。     

The Time-Pressure Illusion: Discretionary Time vs. Free Time

People’s welfare is a function of both time and money. People can – and, it is said, increasingly do – suffer time-poverty as well as money-poverty. It is undeniably true that people feel increasingly time pressured, particularly in dual-earner households. But much of the time devoted to paid and unpaid tasks is over and above that which is strictly necessary. In that sense, much of the time pressure that people feel is discretionary and of their own making. Using data from the 1992 Australian Time Use Survey, this paper demonstrates that the magnitude of this ‘time-pressure illusion’ varies across population groups, being least among lone parents and greatest among the childless and two-earner couples.     

人口迁移、城市圈与房地产价格——基于空间计量学的研究

本文结合我国正兴起的城市圈建设趋势,基于1997~1999年广东省各地级市的数据,构建联立方程模型,利用空间计量方法,研究珠三角城市圈内人口迁移与房地产价格之间的关系。结果发现,不仅传统的收入、消费以及人口迁移等因素可以显著地影响房地产价格水平,而且空间地理因素也可以对城市房地产价格产生显著的影响。     

稳杠杆和稳增长目标下最优货币政策规则

针对货币政策如何对宏观杠杆率作出反应的问题,构建福利损失函数、动态IS-NK-Phillips曲线和自然利率内生决定方程所刻画的宏观经济约束环境,求解引入宏观杠杆率的最优利率和数量规则,并基于中国1996～2020年的季度宏观经济数据,采用GMM方法和State-Space方法分别估计固定参数和时变参数的最优货币政策规则。研究发现,中国最优利率规则和数量规则均具有显著盯住宏观杠杆的政策取向,且最优利率政策操作相比最优数量政策更具主动性; 最优利率规则促增长同时宏观杠杆率较为稳定,而最优数量规则熨平经济波动同时容易引发宏观杠杆率大幅波动; 面对重大经济冲击时,央行更加注重稳增长的同时包容温和通胀和适度杠杆。央行应对宏观杠杆率予以关注,发挥利率政策促增长的同时把好货币供应总闸门,进一步拓宽优化中国利率政策框架,延伸名义利率调控通货膨胀、实体经济和宏观杠杆的宽度,由不稳定规则转变为稳定规则,增强利率政策对宏观杠杆目标的调节功效,从而促进宏观经济可持续高质量发展。     

时间战略:战略管理研究中的一个缺失

时间是嵌入在战略中的一部分,战略具有时间依赖的属性。对基于时间依赖属性的管理认知和战略行动间的互动关系进行了分析,阐述了在组织战略形成、执行和创新过程中微观行动主体与组织行动过程在中观和宏观层面的相互作用,探讨了个体行动者在不同时间认知状态下对组织战略行动产生影响的机理。基于时间视角的战略管理活动,有助于增进对组织战略决策、组织创新、组织动态能力以及企业家创新等议题的深入理解,也有助于推进对管理实践中一些两难问题的认识和处理。